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  • Organic Chemistry  (714)
  • 1980-1984  (714)
  • 1981  (714)
  • 101
    Electronic Resource
    Electronic Resource
    Nucleotide, XVI. Synthese und Eigenschaften von Adenylyl-adenylyl-adenosinen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2392-2406 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleotides, XVI.  -  Synthesis and Properties of Adenylyl-adenylyl-adenosinesThe completely protected adenylyl(2′,5′)adenylyl(2′,5′)adenosines 21 and 22 have been synthesized in preparative scale by the phosphotriester approach applying the o-chlorophenyl and p-nitrophenylethyl group, respectively, as phosphate protective groups. Deprotecting experiments showed more homogeneous reactions with the p-nitrophenylethyl phosphate 22 and gave higher yields of the trimeric A2′p5′A2′p5′A (23). The two isomeric differently linked adenosine trimers A2′p5′A3′p5′A (30) and A3′p5′A2′p5′A (31) have been prepared analogously. Various physical properties of these trinucleoside diphosphates have been determined and compared.
    Notes: Mit Hilfe der Phosphotriester-Methode werden auf zwei verschiedenen Wegen unter Verwendung des o-Chlorphenyl- bzw. p-Nitrophenylethyl-Restes als Phosphat-Schutzgruppe die beiden vollgeschützten Adenylyl(2′,5′)adenylyl(2′,5′)adenosine 21 und 22 in präparativen Mengen dargestellt. Bei den Schutzgruppenabspaltungen zeigt das (p-Nitrophenylethyl)phosphat 22 einheitlichere Reaktionen und liefert das trimere A2′p5′A2′p5′A (23) auch in höherer Ausbeute. Die beiden isomeren unterschiedlich verknüpften trimeren Adenosine A2′p5′A3′p5′A (30) und A3′p5′A2′p5′A (31) werden auf analogen Wegen synthetisiert und verschiedene physikalische Eigenschaften dieser Trinucleosid-diphosphate verglichen.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198119811223
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  • 102
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    Electronic Resource
    Synthese von N-Hydroxyaminosäuren durch Alkylieren von N-Benzyliden-α-aminosäure-methylester-N-oxidenHerrn Prof. Dr. L. Horner zum 70. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1378-1387 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of N-Hydroxy-α-amino Acids by Alkylation of N-Benzylidene-α-amino Acid Methyl Ester N-oxidesThe higher N-benzylidene-α-amino acid methyl ester N-oxides 3c-t were obtained from the lower nitrone esters 3a and b by base induced alkylation in α-position of the N→O-group. The compounds 3 were converted into the N-hydroxy-α-amino acid methyl esters 6 by heating with hydroxylamine hydrochloride in ethanol and into N-hydroxy-α-amino acids 7 with concd. hydrochloric acid. - Compound 3d was, on heating in toluene, converted to methyl 1-aza-7-oxabicyclo-[2.2.1]heptanecarboxylate 8 by intramolecular cycloaddition.
    Notes: Aus den einfachen Nitronestern 3a und b erhielt man durch baseninduzierte Alkylierung in α-Stellung zur N→O-Gruppe die höheren N-Benzyliden-α-aminosäure-methylester-N-oxide 3c-t. Durch Erhitzen mit Hydroxylamin-hydrochlorid in Ethanol gewann man daraus die N-Hydroxy-α-aminosäure-methylester 6, durch Hydrolyse mit konz. Salzsäure die N-Hydroxy-α-aminosäuren 7. - Die Verbindung 3d lieferte beim Erhitzen in Toluol durch intramolekulare Cycloaddition den 1-Aza-7-oxabicyclo[2.2.1]heptancarbonsäure-methylester 8.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198119810806
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  • 103
    Electronic Resource
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    Synthese und Umlagerung 1-substituierter Bicyclo[2.2.0]hexaneHerrn Prof. Dr. L. Horner zum 70. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1394-1406 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Rearrangement of 1-Substituted Bicyclo[2.2.0]hexanesStarting from 7-oxobicyclo[2.2.1]heptane-1-carbonyl chloride (3), bicyclo[2.2.0]hexane-1-carboxylic acid (9) was prepared via Hunsdiecker degradation and Favorskii rearrangement. The conversion of 9 to 1-methoxybicyclo[2.2.0]hexane (15) via methyl ketone 12 and acetate 13 was complicated by the facile homoketonization of the elusive bicyclo[2.2.0]hexane-1-ol (14). Similarly, bicyclo[2.2.0]hexane-1-amine readily underwent hydrolysis whereas N,N-dimethylbicyclo-[2.2.0]hexane-1-amine (17) proved to be more resistant. Thermolysis of methyl bicyclo[2.2.0]-hexane-1-carboxylate (10) revealed a „normal“ rate enhancement (ΔEaca.6 kcal/mol = 25 kJ/mol). The effects of 1 -acetoxy, 1-methoxy and 1-dimethylamino groups on the rate of rearrangement were unexpectedly small.
    Notes: Ausgehend von 7-Oxobicyclo[2.2.1]heptan-1-carbonylchlorid (3) wurde Bicyclo[2.2.0]hexan-1-carbonsäure (9) durch Hunsdiecker-Abbau und Favorskii-Umlagerung dargestellt. Die Umwandlung von 9 in 1-Methoxybicyclo[2.2.0]hexan (15) über das Methylketon 12 und Acetat 13 wurde durch die leichte Homoketonisierung des nicht isolierbaren Bicyclo[2.2.0]hexan-1-ols (14) erschwert. Entsprechend hydrolysierte Bicyclo[2.2.0]hexan-1-amin leicht, während sich N,N-Dimethylbicyclo[2.2.0]hexan-1-amin (17) als beständiger erwies. Die Thermolyse von Bicyclo-[2.2.0]hexan-1-carbonsäure-methylester (10) zeigte eine „normale“ Beschleunigung (ΔEaca.6 kcal/mol = 25 kJ/mol). Der Einfluß von 1-Acetoxy-, 1-Methoxy- und 1-Dimethylaminogruppen auf die Umlagerungsgeschwindigkeit war unerwartet gering.
    Additional Material: 6 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198119810808
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  • 104
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    Organische Elektrochemie, III. Chemische und elektrochemische Synthese von 1,4-Diacyl-1,4-dihydropyrazinen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1451-1456 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Electrochemistry, III1) Chemical and Electrochemical Synthesis of 1,4-Diacyl-1,4-dihydropyrazinesPyrazine (1) is converted by cathodic reduction in aprotic solvents in the presence of acylating agents into 1,4-diacyl-1,4-dihydropyrazines (5-8). The same reaction proceeds chemically with zinc dust in anhydrides yielding besides 5 and 6 also 1,4-diformyl-1,4-dihydropyrazine (9). The compounds have been characterized by UV-, NMR-, and mass spectra.
    Notes: Pyrazin (1) kann durch kathodische Reduktion in aprotischen Lösungsmitteln mit Tetraethyl-ammonium-bromid als Leitsalz und bei Gegenwart von Acylierungsmitteln in 1,4-Diacyl-1,4-di-hydropyrazine (5-8) übergeführt werden. Chemisch gelingt dieselbe Reaktion mit Zinkstaub in Anhydriden, wobei außer 5 und 6 auch 1,4-Diformyl-1,4-dihydropyrazin (9) erhalten werden konnte. Die Verbindungen werden durch UV-, NMR- und Massenspektren charakterisiert.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119810816
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  • 105
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    N-Acyldehydro-α-aminosäuren aus N-Formyldehydro-α-amino-säure-methylestern (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1469-1475 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N-Acyl Dehydro-α-amino Acids from N-Formyl Dehydro-α-amino Acid EstersOn treatment with methyl potassioisocyanoacetate (2), aldehydes and ketones 1 give N-anionized N-formyl dehydro-α-amino acid methyl esters 3. Compound 3 with R1 = CH3, R2 = H is obtained by base induced ring opening of methyl 2-oxazoline-4-carboxylate 5.  -  Acylation of 3, followed by deformylation of the intermediates 6, yields N-acyl dehydro-α-amino acid methyl esters 7 which can be hydrolyzed to the N-acyl dehydro-α-amino acids 8.
    Notes: Aus Aldehyden und Ketonen 1 erhält man mit Kalioisocyanessigsäure-methylester (2) durch Formylaminomethylenierung die am Stickstoff anionisierten N-Formyldehydro-α-aminosäure-methylester 3. Für 3 mit R1 = CH3 und R2 = H ist die baseninduzierte Ringöffnung des 2-Oxazolin-4-carbonsäure-methylesters 5 günstiger.  -  Durch N-Acylierung von 3, gefolgt von Entformylierung der Zwischenstufen 6, erhält man die N-Acyldehydro-α-aminosäureester 7, die zu den N-Acyldehydro-α-aminosäuren 8 hydrolysierbar sind.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119810818
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  • 106
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    Nucleoside, XXXVI. Synthese und Eigenschaften des 4-Amino-8-β-D-ribofuranosyl-7(8H)-pteridinons sowie seiner 2- und 6-Phenylderivate (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1457-1468 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleosides, XXXVI1). - Synthesis and Properties of 4-Amino-8-β-D-ribofuranosyl-7(8H)-pteridinone and its 2- and 6-Phenyl Derivatives4-Amino-7(8H)-pteridinone (5) and its 2- and 5-phenyl derivatives (6-8) are converted by the Silyl-Hilbert-Johnson method to the corresponding acylated N-8-ribosides (15-18, 23, 24). Deacylation led to the free pteridine nucleosides (19-22, 25) which can be regarded as adenosine analogs. The compounds were characterized by UV and CD spectra as well as pK determinations. The nucleosides 19-21 and 25 are light-sensitive and are cleaved photolytically at the glycosidic linkage.
    Notes: 4-Amino-7(8H)-pteridinon (5) und seine 2- und 6-Phenyl-Derivate (6-8) werden nach der Silyl-Hilbert-Johnson-Methode zu den entsprechenden acylierten N-8-Ribosiden (15-18, 23, 24) um-gesetzt. Entacylierung liefert die freien Pteridinnucleoside (19-22, 25), die als Strukturanaloge des Adenosins angesehen werden können. Die Verbindungen werden durch UV- und CD-Spektren sowie pK-Bestimmungen charakterisiert. Die Nucleoside 19-21 und 25 sind sehr licht-empfindlich und erleiden in Lösung leicht Photolyse der glycosidischen Bindung.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119810817
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  • 107
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    Über unsymmetrisch N-substituierte Bispidine (3,7-Diazabicyclo[3.3.1]nonane), IIIHerrn Prof. Dr. Herbert Grünewald zum 60. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1699-1704 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Unsymmetrically N-Substituted Bispidines (3,7-Diazabicyclo[3.3.1]nonanes), III1)The diastereoisomeric mixture 4 of 3,7-diazabicyclo[3.3.1]nonane-2,4,6,8-tetraones, in which the difference between the two aliphatic bridge substituents is sufficiently large, has been separated into the pure components. Their configurations have been determined by X-ray structural analysis of 4a. In the case of 5, where the two bridge substituents are very similar, the separation was not possible.
    Notes: Das Diastereomerengemisch 4 von 3,7-Diazabicyclo[3.3.1]nonan-2,4,6,8-tetraonen mit unterein-ander genügend verschiedenen aliphatischen Brückensubstituenten wird in die reinen Komponenten aufgetrennt. Die Konfigurationsbestimmung erfolgt durch Röntgenstrukturanalyse von 4a. Im Fall 5 mit sehr ähnlichen aliphatischen Brückensubstituenten gelingt die Trennung nicht mehr.
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    URL: http://dx.doi.org/10.1002/jlac.198119810919
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  • 108
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    Pheromone, XXXII. Bausteine zur Darstellung zweifach ungesättigter Schmetterlings-pheromoneHerrn Prof. Dr. L. Horner zum 70. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1705-1720 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pheromones, XXXII.  -  Synthons for the Preparation of Bisolefinic Lepidoptera PheromonesThe synthesis of α,ω-bifunctional starting compounds as well as (Z) and (E) configurated unsaturated synthons obtained by Wittig reaction, Michael addition, acetylenic approach, or Crombie reaction is described. These substances are required for the preparation of bisolefinic sex pheromones using a „unitized construction principle“.
    Notes: Die Darstellung α,ω-bifunktioneller Ausgangsverbindungen sowie (Z)- und (E)-konfigurierter, ungesättigter Synthesebausteine, die man mittels Wittig-Reaktion, Michael-Addition, Acetylen-synthese oder Crombie-Reaktion erhält, wird beschrieben. Diese Verbindungen werden im Rahmen eines „Baukastensystems“ zur Synthese bisolefinischer Sexualpheromone benötigt.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198119810920
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  • 109
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    Masthead (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811001
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  • 110
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    1,1′,2,2′-Tetrathiafulvalene, II. Thieno[3,2-b]thiophene aus 1,2-Dithiol-Verbindungen; 3H-1,2-Dithiol-3-ylidene (1,2-Dithiol-3-carbene) als mutmaßliche ZwischenstufenHerrn Professor Dr. A. Lüttringhaus zum 75. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1729-1750 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,1′,2,2′-Tetrathiafulvalenes, II.  -  Thieno[3,2-b]thiophenes from 1,2-Dithiole Compounds; 3H-1,2-Dithiol-3-ylidenes (1,2-Dithiole-3-carbenes) as Supposed Intermediates3,3′-Bi(3H-1,2-Dithiolylidenes) (1,1′,2,2′-Tetrathiafulvalenes) 5 are not obtainable with the following reactions which, however, have proved to be a good approach to the corresponding 1,3-
    Notes: 3,3′-Bi(3H-1,2-dithiolylidene) (1,1′,2,2′-Tetrathiafulvalene) 5 können nicht durch die folgenden, jedoch für die Synthese der entsprechenden 1,3-Isomeren 3 bewährten Reaktionen, erhalten werden: 1) Deprotonierung von 1,2-Dithiolylium-Kationen 4, 2) Pyrolyse der Alkaliderivate von 1,2-Dithiol-2-on-tosylhydrazonen 26 (Bamford-Stevens-Reaktion) oder 3) partielle Entschwefelung von 1,2-Dithiol-3-thionen 6 mit Verbindungen des dreiwertigen Phosphors. Vielmehr entstehen bei diesen Reaktionen mit den 1,2-Isomeren stets Thieno[3,2-b]thiophene 8, begleitet von den dazugehörigen 1,2-Dithiol-3-thionen 6 (1,2-Trithionen), im Fall 26 auch von Azinen 27. Partielle Entschwefelung von 6 mit Kupferbronze liefert anstatt 5 wieder Thieno[3,2-b]thiophene 8. Bei der Thermolyse des 1,2-Dithiolylium-iodids 34 bzw. 34′ bildet sich das Thieno[3,2-b]thiophen 8a gemeinsam mit dem 1,2-Trithion 6a. Überraschend entstehen auch bei der P4S10-Schwefelung von „Desaurinen“ 37 entsprechende Thienothiophene, daneben 1,2-Dithiol-3-thione 6.  -  Für eine aus 1-Morpholinocyclohexen (18) und dem 1,2-Dithiolylium-Kation 4a (X = ClO4) entstehende Verbindung, die formal als 1:1-Addukt aus dem Carben 9a und dem Enamin erscheint, wird die Konstitution 19 vorgeschlagen.
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    URL: http://dx.doi.org/10.1002/jlac.198119811002
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  • 111
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    Aminoethinylierungen, 2. Synthese von (Aminoethinyl)ketonen über β-stannylierte Inamine (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1907-1927 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminoethynylations, 21).  -  Synthesis of (Aminoethynyl) Ketones via β-Stannylated YnaminesThe acid chlorides 1 react with (stannylethynyl)amines 2 under rather mild conditions to give the (aminoethynyl) ketones 4-7 and the chlorostannanes 8. With phthalic anhydride the interesting stannyl 2-(anilinopropioloyl)benzoates 4r′ and 5r′ are formed. Derivatives of chloroformic acid show reduced reactivity towards the β-stannylated ynamines 2; only the corresponding alkyl 3-amino-propiolates (e. g. 10) are obtainable via 2. In order to synthesize propiolic acid amides or amidines (e. g. 12) the more nucleophilic lithium aminoacetylides 11 have to be used. The β-silylated ynamines 13 partly react with highly electrophilic acid chlorides 1 in acetonitrile (instead of ether) to yield acyl ynamines 4-6. The new synthesis of (aminoethynyl) ketones via the β-stannylated ynamines 2 is compared with other methods of preparation and its character as a method of chain prolongation is revealed.
    Notes: Die Säurechloride 1 reagieren mit (Stannylethinyl)aminen 2 unter milden Bedingungen zu den (Aminoethinyl)ketonen 4-7 und den Chlorstannanen 8. Mit Phthalsäureanhydrid werden die 2-(Anilinopropioloyl)benzoesäure-stannylester 4r′ und 5r′ erhalten. Chlorameisensäurederivate zeigen verminderte Reaktivität; so sind nur die 3-Aminopropiolsäureester (z. B. 10) synthetisierbar. Zur Darstellung von Propiolamiden bzw. -amidinen (z. B. 12) müssen Lithium(aminoacetylide) (z. B. 11) eingesetzt werden. Die β-silylierten Inamine 13 reagieren mit stark elektrophilen Säurechloriden 1 in Acetonitril teilweise zu den Acylinaminen 4-6. Die neue Acylinaminsynthese wird mit anderen Darstellungsmethoden verglichen und ihr Charakter als Kettenverlängerungsmethode aufgezeigt.
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    URL: http://dx.doi.org/10.1002/jlac.198119811102
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  • 112
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    Kinetic study of the alkaline hydrolysis of 2,2,2-trichloro-1-hydroxyethyl substituted phosphinates and phosphine oxidesDedicated to Professor Leopold Horner on the occasion of his 70th Birthday. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1967-1972 
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    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetische Untersuchungen zur Hydrolyse von (2,2,2-Trichlor-1-hydroxyethyl)phosphinsäureestern und entsprechenden PhosphanoxidenDie alkalische Hydrolyse von (2,2,2-Trichlor-1-hydroxycthyl)phosphinsäureestern verläuft nach dem gleichen Schema wie bei entsprechenden Phosphonsäureestern [Dipterex (1) und der analoge Ethylester] unter Bildung von O - P -C-Umlagerungsprodukten. Die Diphenyl- und Diethyl-phosphanoxid-Derivate 7 bzw. 6 hydrolysieren nach einem anderen Mechanismus, bei dem disubstituierte Phosphanoxide und Dichloressigsäure entstehen.
    Notes: The study shows that the alkaline hydrolysis of 2,2,2-trichloro-1-hydroxyethyl substituted phosphinates follows the same route as the corresponding phosphonates, Dipterex (1) and its ethyl analogue, giving O - P - C rearrangement products. The corresponding diphenyl and diethyl phosphine oxide derivatives 7 or 6, respectively, are hydrolyzed according to another reaction mechanism resulting in secondary phosphine oxides and dichloroacetic acid.
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    URL: http://dx.doi.org/10.1002/jlac.198119811105
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  • 113
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    Synthese von 3-Methoxy-18-methyl-1,3,5(10),15-östratetraen-17α-ol (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1973-1981 
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    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 3-Methoxy-18-methyl-1,3,5(10),15-östratetraen-17α-olThe transformation of the 16α,17-epoxide 4 into the allyl alcohol 9 has been achieved via the bromohydrin 5 and the tetrahydropyranyl ether 6 or in a „one-pot“ procedure by oxidation of the 16β-phenyl selenide 12 to the products 14, 16, and 18. From the two 16β-phenyl sulfoxides 13 and 15, only the sulfoxide 13 with R configuration reacts thermally to yield the allyl alcohol 9 which can also be prepared from the piperidine N-oxide 8. The configuration of the phenyl sulfoxides 13 and 15 as well as of the corresponding phenyl selenoxides 14 and 16 has been determined by circular dichroism investigations. For the first time it has been possible to isolate a steroidal selenium analog 18 corresponding to the phenyl sulfone 17.
    Notes: Die Überführung des 16α,17-Epoxids 4 in den Allylalkohol 9 gelingt über das Bromhydrin 5 und den Pyranylether 6 oder im Eintopfverfahren über das 16β-Phenylselenid 12 und dessen Oxidationsprodukte 14, 16 und 18. Von den 16β-Phenylsulfoxiden 13 und 15 reagiert thermisch nur das (R)-konfigurierte 13 zum Allylalkohol 9, der sich ebenfalls aus dem Piperidin-N-oxid 8 herstellen läßt. Die konfigurative Zuordnung der Phenylsulfoxide 13 und 15 sowie der entsprechenden Phenylselenoxide 14 und 16 ließ sich durch CD-Spektren ermitteln. Erstmalig konnte bei Steroiden ein dem Phenylsulfon 17 entsprechendes Selen-Analogon 18 isoliert werden.
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    URL: http://dx.doi.org/10.1002/jlac.198119811106
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  • 114
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    Lichtinduzierte Reaktionen an Morphinderivaten, 2. Photoreaktivität von Codeinonen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2002-2008 
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    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Light-induced Reactions of Morphine Derivatives, 2.  -  Photoreactivity of CodeinonesThe photochemical instability of the ether bridge of codeinone derivatives is due to the strain of the all-carbon ring skeleton. Irradation of the codeinones 1, 2, and 8 with light of the wavelength 254 nm causes solvolytical cleavage of the ether bridge. In contrast, derivatives with a sixmembered ring C are photostable.
    Notes: Die photochemische Labilität der Etherbrücke von Codeinonderivaten wird durch die Spannung des Kohlenstoffringgerüstes bedingt. Bei Bestrahlung der Codeinone 1, 2 und 8 mit Licht der Wellenlänge 254 nm wird die Etherbrücke solvolytisch geöffnet. Derivate mit sechsgliedrigem Ring C hingegen sind photostabil.
    Type of Medium: Electronic Resource
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    Der Quincyte-Farbstoff (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 842-848 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Quincyte DyeTo the Quincyte dye (QF) the bis(isopropylamphinaphthochinone) structure2 is assigned. As a quinone the dyestuff is able to add pyrrole derivatives.
    Notes: Dem roten Quincyte-Farbstoff (QF) wird die Bis(isopropylamphinaphthochinon)-Struktur2 zugeordnet. Als Chinon vermag der Farbstoff mit Pyrrolderivaten zu reagieren.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119810509
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    Reaktionen von Pyrrolen mit α,β-ungesättigten Aldehyden und Ketonen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 849-857 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Pyrroles with α,β-Unsaturated Aldehydes and KetonesReactions of α,β-unsaturated aldehydes and ketones with pyrrole derivatives yields the (3-oxoalkyl)pyrroles2, 6, and7 as well as the tris(pyrrolyl)propanes3 and4. Compound3a is oxidized to give the tripyrryltrimethine5 and the dipyrryltrimethine1a, respectively. The Bucherer hydantoin reaction is recognized to be suitable for the characterization of (3-oxoalkyl)pyrroles.
    Notes: Durch Reaktion α,β-ungesättigten Aldehyden und Ketonen mit Pyrrolen werden die (3-Oxoalkyl)-pyrrole2, 6 und7 sowie die Tris(pyrrolyl)propane3 und4 erhalten.3a läβt sich zum Tripyrryltrimethin5 bzw. Dipyrryltrimethin 1a oxidieren. Bucherers Hydantoinreaktion wird zur Charakterisierung von (3-Oxoalkyl)pyrrolen als geeignet erkannt.
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    4-Alkyl(Aryl)-λ3-phosphorine aus Butoxy-4-alkyl(aryl)-4-methoxy-1,4-dihydrophosphorinenHerrn Prof. Dr. A. Roedig zum 70. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 919-942 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 4-Alkyl(Aryl)-λ3-phosphorins from Butoxy-4-alkyl(aryl)-4-methoxy-1,4-dihydrophosphorinsThe (1 Z,4Z)-1,5-dilithio-3-R-3-methoxy-1,4-pentadienes9 have been obtained by cleavage of 1,1-dibutyl-4-R-4-methoxy-1,4-dihydrostannis1 with butyllithium. Reaction of9 with butoxydichlorophosphorane at -78°C gives the cis/trans-isomeric 1-butoxy-4-R-4-methoxy-1,4-dihydrophosphorins17. Their reduction with LiAlH4 leads to the monosubstituted 4-R-λ3-phosphorins3 [R = CH3, C2H5, C(CH3)3, cyclo-C6H11, C6H5] in good yields. - The 1H-NMR spectra of the λ3-phosphorins are analyzed and computer-simulated, the 13C-NMR, UV, and mass spectra are discussed in detail.
    Notes: Die aus 1,1-Dibutyl-4-R-4-methoxy-1,4-dihydrostanninen1 durch Spaltung mit BuLi erhältlichen (1 Z,4Z)-1,5-Dilithio-3-R-3-methoxy-1,4-pentadiene9 reagieren mit Butoxydichlorphosphan bei -78°C zu den cis/trans-isomeren 1-Butoxy-4-R-4-methoxy-1,4-dihydrophosphorinen17. Durch deren Reduktion mit LiAlH4 werden in guten Ausbeuten die monosubstituierten 4-R-λ3-phosphorine3 [R = CH3, C2H5, C(CH3)3, cyclo-C6H11, C6H5] erhalten. - Die 1H-NMR-Spektren der λ3-Phosphorine werden analysiert und simuliert, die 13C-NMR-, UV- und Massenspektren werden ausführlich diskutiert.
    Additional Material: 6 Ill.
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    Masthead (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119810601
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    Dreigliedrige Heterocyclen Ein Diazaphosphiridin-3-oxidHerrn Professor S. Hünig zum 60. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 967-976 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Three-membered Heterocycles, 11 1a).  -  A Diazaphosphiridine 3-OxideA survey of phosphorus containing systems which may exist as three-membered rings reveals that, in contrast to the hypothetical three-membered rings consisting of σ3λ3V-phosphorus and one or two more electronegative atoms, aza-σ4λ5-phosphiridines and diaza-σ4λ5-phosphiridines should be more stable than their acyclic isomers. The alkoxides12a-12c transform the N-chlorophosphondiamide11 into the phosphonate hydrazides13a-13c, and with strongly hindered, non-nucleophilic alkoxides, e.g.12d or12e, from11 is obtained the diazaphosphiridine oxide14. From its temperature-dependent 1H-NMR spectrum an activation barrier of δG235 = 49 kJ/mole for the diastereotopomerization of the trans-N-tert-butyl groups via pyramidal nitrogen inversion has been calculated. In benzene,14 is stable up to 125°C. At 145-155°C undefined decomposition occurs affording 0.6 moles of 2-methylpropene. Methanol very rapidly opens the ring of14 yielding quantitatively the phosphonate hydrazide13a.
    Notes: Ein überblick über Phosphor enthaltende Systeme, die in einer Dreiringstruktur vorliegen können, zeigt, daβ im Gegensatz zu den hypothetischen σ3λ3-Phosphor-Dreiringen mit einem oder zwei elektronegativeren Atomen Aza-σ4λ5-phosphiridine und Diaza-σ4λ5-phosphiridine stabiler als ihre acyclischen Isomere sein sollten. Die Alkoholate12a-12c überführen das N-Chlorphosphondiamid11 in die Phosphonesterhydrazide13a-13c, mit sterisch stark gehinderten, nichtnucleophilen Alkoholaten wie12d oder12e erhält man aus11 das Diazaphosphiridinoxid14. Aus seinem temperaturabhängigen 1H-NMR-Spektrum läβt sich eine Aktivierungsbarriere von δ235 = 49 kJ/mol für die Diastereotopomerisierung der trans-ständigen N-tert-Butylgruppen durch pyramidale Stickstoff-Inversion errechnen.14 ist in Benzol bis 125°C stabil. Bei 145-155°C tritt undefinierte Zersetzung ein, die 0.6 mol 2-Methylpropen liefert. Methanol öffnet sehr rasch den Ring von14 und bildet quantitativ das Phosphonesterhydrazid13a.
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    Hochselektive Totalsynthese von 19-Nor-Steroiden mit photochemischer Schlüsselreaktion: Racemische Zielverbindungen1,4) (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2335-2371 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Highly Selective Total Synthesis of 19-Nor-Steroids via a Photochemical Key Reaction: Racemic Target Compounds1,4)Ring A and ring D building blocks 17b and rac-15, easily available from m-cresyl methyl ether (19a) or (E)-1,4-dibromo-2-butene (13b) and methyl malonate (14a), respectively, react by Michael addition affording the key compound rac-9a. The latter compound by successive photoenolization, intramolecular Diels/Alder reaction, and dehydration furnishes the pretarget compounds rac-5 and rac-6. From here the 19-norsteroids rac-estrone (rac-1a), rac-19-norandrost-4-ene-3,17-dione (rac-2a), rac-estradiol-17β (rac-3a), and rac-19-nortestosterone (rac-4a) are optionally accessible (cf. schemes 1 and 2 as well as tables 3 and 4).
    Notes: Die Ring A- und Ring D-Bausteine 17b und rac-15, die bequem aus m-Kresolmethylether (19a) sowie (E)-1,4-Dibrom-2-buten (13b) und Malonsäure-dimethylester (14a) zugänglich sind, fügen sich in einer Michael-Addition zur Schlüsselverbindung rac-9a zusammen. Letztere reagiert nacheinander durch Photoenolisierung, intramolekulare Diels/Alder-Reaktion und Dehydratisierung zu den Präzielverbindungen rac-5 und rac-6. Von hier aus erhält man wahlweise die 19-Nor-Steroide rac-Östron (ra-1a), rac-19-Norandrost-4-en-3,17-dion (rac-2a), rac-Östradiol-17β (rac-3a) und rac-19-Nortestosteron (rac-4a) (s. Schemata 1 und 2 sowie Tab. 3 und 4).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119811220
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    Über die Inhaltsstoffe des grünen Knollenblätterpilzes, LIX. Die Raumstruktur der Phallotoxine (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2318-2334 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Components of the Green Deathcap Toadstool (Amanita phalloides), LIX.  -  The Spatial Structure of PhallotoxinsThe thioether bridge [CH2 - S - C(α-indole)] in the phallotoxin molecule is an inherently dissymmetric chromophore responsible for the positive Cotton effects centered around 290 nm in CD spectra. The helicity of this structural element, M- or P-, could not be recognized unambigously by 1H-NMR analysis previously performed. A less complex cyclic thioether peptide, 2-mercapto-L-tryptophylglycylcysteine cyclic (1 → 3) sulfide (2a) exhibits a CD spectrum showing the Cotton effects around 290 nm nearly exactly in a negative sense as mirror image of those of the phallotoxins (Figure 1). The structural analysis by 360 MHz 1H-NMR suggested M-helicity of the chromophore. Unquestionable proof was obtained by X-ray structure analysis of the N-p-bromo benzenesulfonyl derivative 2c (which shows the same Cotton effects as 2a) resulting in a M-helical thioether moiety of 2c(and2s. Therefore to the phallotoxins with analogous but positive Cotton effects around 290 nm a P-helical thioether structure must be ascribed. The presence of an additional chiral centre in the peptide ring(2b: L-alanine instead of glycine in 2a) does not influence the shape of the CD spectrum.
    Notes: Die Thioetherbrücke [CH2 - S - C(α-indol)] in den Phallotoxinen ist ein inhärent dissymmetrischer Chromophor, der die positiven Cottoneffekte um 290 nm im CD-Spektrum verursacht. Bei einer früheren Strukturanalyse durch 1H-NMR konnte die M- oder P-Helizität dieses Strukturelements nicht eindeutig bestimmt werden. Das einfacher gebaute cyclische Thioethertripeptid 2-Mercapto-L-tryptophylglycylcystein-cyclosulfid (1 → 3) (2a) weist im CD-Spektrum um 290 nm zu denen der Phallotoxine genau spiegelbildliche negative Cottoneffekte (Abb. 1) auf. Die Strukturanalyse von 2a durch 1H-NMR (360 MHz) führte zu einem Strukturvorschlag mit M-Helizität. Das N-p-Brombenzolsulfonylderivat 2c mit analogem CD-Spektrum bildete mit Aceton Kristalle, die zur Röntgenstrukturanalyse geeignet waren. Die dadurch erhaltene Raumformel zeigt für das fragliche Strukturelement negative M-Helizität. Demnach enthalten die Phallotoxine den spiegelbildlich analogen Chromophor mit positiver P-Helizität. Die Einführung eines weiteren chiralen Zentrums in den Peptidring (2b: L-Alanin statt Glycin in 2a) hat auf die Gestalt des CD-Spektrums keinen Einfluß.
    Additional Material: 6 Ill.
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    1,2,4,6-Tetraorganophosphorinylnickel-KomplexeHerrn Professor Dr. Karl Dimroth zum 70. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1147-1161 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,2,4,6-Tetraorganophosphorinylnickel ComplexesThe reaction of nickel(II) acetylacetonate with 2,4,6-triphenylphosphabenzene (1) and ethoxy(diethyl)aluminium results in the formation of [bis(1-ethyl-2,4,6-triphenylphosphorinyl)nickel]-(ethylene)-P,P′-nickel (2). The ethylene molecule in 2 can be displaced by 3,3-dimethylcyclo-propene (3), the alkynes 4 and 5, tricyclohexylphosphane (6) or 1 to give the corresponding nickel complexes 7-11. The two phosphorinyl ligands in these complexes bridge a Ni-Ni unit in a sandwich form.  -  1H- and 31P-NMR measurements indicate that the η3-allyl and ene functions in 7-11 as well as in bis(1-ethyl-2,4,6-triphenylphosphorinyl)iron (13) undergo valence isomerization. The ene moiety in 13 is complexed to the iron.
    Notes: [Bis(1-ethyl-2,4,6-triphenylphosphorinyl)nickel](ethylen)-P,P′-nickel (2) wird durch Reaktion von Nickel(II)-acetylacetonat mit 2,4,6-Triphenylphosphabenzol (1) und Ethoxy(diethyl)aluminium erhalten. Bei 2 läβt sich Ethylen durch 3,3-Dimethylcyclopropen (3), die Alkine 4 und 5, Tri-cyclohexylphosphan (6) oder 1 zu den entsprechenden Nickelkomplexen 7-11 verdrängen. In diesen Komplexen überbrücken beide Phosphorinylliganden sandwichartig eine Ni  -  Ni-Einheit.  -  Nach 1H- und 31P-NMR-Messungen erfolgt in den Phosphorinyl-Liganden ber 2, 7, 8 und 11 sowie bei Bis(1-ethyl-2,4,6-triphenylphosphorinyl)eisen (13) Valenzisomerisierung zwischen η3-Allyl- und En-Funktion. Bei 13 ist der En-Teil an Fe komplex gebunden.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119810619
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    Stabile Enole von α-[Aryl(Alkyl)oxy]dibenzoylmethanenHerrn Prof. Dr. K. Dimroth zum 70. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1172-1185 
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    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stable Enols of α-[Aryl(Alkyl)oxy]dibenzoylmethanesThe enols 13a-m of α-(aryloxy)- and α-[Aryl(Alkyl)oxy]dibenzoylmethanes 4a-m are obtained by decomposition of the copper chelates 11a-m with sulfuric acid. The copper compounds are synthesized either by ester condensation of the acetophenones 6h-m with phenyl benzoate (7) or by nucleophilic substitution of α-bromodibenzoylmethane (9) with the phenols 10a-g. The enolates 8, primarily formed in the presence of sodium hydride or triethylamine, respectively, are directly converted into the chelates 11 with copper(II) acetate. The enols 13 are characterized by isomerization to the β-diketones 4 as well as by bromination to 12.
    Notes: Die Enole 13a-m von α-(Aryloxy)- und α-(Alkyloxy)dibenzoylmethanen 4a-m werden durch Zerlegung der Kupferchelate 11a-m mit Schwefelsäure erhalten. Zu den Kupferverbindungen gelangt man entweder durch Esterkondensation der Acetophenone 6h-m mit Benzoesäure-phenylester (7) oder durch nukleophile Substitution von α-Bromdibenzoylmethan (9) mit den Phenofen 10a-g. Die in Gegenwart von Natriumhydrid bzw. Triethylamin zunächst gebildeten Enolate 8 lassen sich direkt mit Kupfer(II)-acetat in die Chelate 11 umwandeln. Die Enole 13 sind durch Isomerisierung zu den β-Diketonen 4 sowie durch die Bromierung zu 12 charakterisiert.
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    URL: http://dx.doi.org/10.1002/jlac.198119810703
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    Synthesen mit α-metallierten Isocyaniden, IL Phosphoranaloga von Aminosauren und Peptiden, VI Synthese von Oxazolyl- und Thiazolylphosphonsäurediethylestern (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1186-1189 
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    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses with α-Metalated Isocyanides, IL1).  -  Phosphorus Analogs of Amino Acids and Peptides, VI2).  -  Synthesis of Diethyl Oxazolyl- and ThiazolylphosphonatesFrom α-metalated diethyl isocyanomethylphosphonate (1) the diethyl oxazol-4-ylphosphonates 7 have been obtained by reaction with acyl chlorides or imidazolides, and diethyl (5-methylthiothiazol-4-yl)phosphonate (11) by reaction with carbon disulfide and subsequent addition of methyl iodide.
    Notes: Aus α-metalliertem Isocyanmethylphosphonsäure-diethylester (1) erhielt man mit Acylchloriden oder -imidazoliden (Typ 3) die Oxazol-4-ylphosphonsäure-diethylester 7, mit Schwefelkohlenstoff gefolgt von Methyliodid-Addition (5-Methylthiothiazol-4-yl)phosphonsäure-diethylester (II).
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    Intermolekulare Silylgruppen-Wanderung bei (Trimethylsiloxy)-enonen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1234-1243 
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    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Intermolecular Migration of Silyl Groups in (Trimethylsiloxy)enonesCrossover experiments prove that the silyl groups in quadratic acid bis(trimethylsilyl ester) (1) undergo rapid intermolecular migrations. This causes the two 13C-NMR signals of the four-membered ring, which appear at 35°C as singlets, to coalesce at 83°C and to reappear as a single signal above 170°C. The activation energy amounts to 16.9 kcal/mol. Other bis(silylated) ketoenols 2, 3, 4, and 5 show no dynamic effects; nevertheless, they rearrange intermolecularly.
    Notes: Wie Kreuzungsversuche beweisen, gehen die Silylgruppen des Quadratsäure-bis(trimethylsilylesters) (1) rasche intermolekulare Wanderungen ein. Dies hat zur Folge, daβ im 13C-NMR-Spektrum die bei 35°C als zwei Singuletts erscheinenden Signale des Vierrings bei 83°C koaleszieren und oberhalb von 170°C als einziges Signal erscheinen. Die Aktivierungsenergie beträgt dabei 16.9 kcal/mol. Andere bis(silylierte) Ketoenole 2, 3, 4 und 5 zeigen dagegen keine dynamischen Effekte, lagern jedoch intermolekular um.
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    Einfluß der Solvatisierung bei Umsetzungen von Nitrosobenzol mit Kalium-tert-butylat und anderen Basen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1271-1284 
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    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Effect of Solvation on the Reaction of Nitrosobenzene with Potassium tert-Butoxide and Other BasesThe reaction of nitrosobenzene (1) with potassium tert-butoxide (2) proceeds in benzene in the presence of crown ether or in tert-butyl alcohol via the dissociated ion 13a whereas in benzene alone the associated species 12 is formed.  -  Using tert-butyl alcohol as solvent, azoxybenzene (3), N-(4-nitrosophenyl)-N-phenylhydroxylamine (4), and N-phenylhydroxamic acid (5) are obtained; the nitrosobenzene anion radical 7 and methylphenylaminyl oxide (8a) were identified by ESR spectroscopy. The formation of 7 and 8a and their subsequent reactions are discussed.  -  Reactions in benzene yield mainly N-phenyl(2-nitrophenyl)amine (6) together with 4, but no 3 is formed. Instead of the radical 7 which cannot be detected in benzene (even not if 1 is treated with potassium-sodium alloy) another radical is generated for which the structure 11 is suggested.
    Notes: Die Reaktion zwischen Nitrosobenzol (1) und Kalium-tert-butylat (2) verläuft in Benzol bei Gegenwart von Kronenether sowie in tert-Butylalkohol über das dissoziierte lon 13a, in Benzol allein dagegen über die assoziierte Spezies 12.  -  In tert-Butylalkohol entstehen Azoxybenzol (3), N-(4-Nitrosophenyl)-N-phenylhydroxylamin (4) und N-Phenylformhydroxamsäure (5); das Nitrosobenzol-Anionradikal 7 und Methylphenylaminyloxid (8a) können ESR-spektroskopisch nachgewiesen werden. Die Bildung und Folgereaktionen von 7 und 8a werden diskutiert.  -  In Benzol wird N-Phenyl-(2-nitrophenyl)amin (6) als Hauptprodukt gebildet; daneben entsteht noch 4 aber nicht 3. Das Radikal 7 kann in Benzol (auch bei Reduktion von 1 mit Kalium-Natrium-Legierung) nicht beobachtet werden; stattdessen tritt ein Radikal auf, dem die Struktur 11 zugeschrieben wird.
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    URL: http://dx.doi.org/10.1002/jlac.198119810714
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    Masthead (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119810801
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    6-Cyanuracile aus 5-Diazouracilen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1429-1432 
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    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Treatment of the methanol adduct 1a of 5-diazouracil with aqueous potassium cyanide provides 6-cyanouracil (3a) with concomitant evolution of nitrogen. The reaction of aqueous hydrogen cyanide with 1 a forms 6-cyano-5-diazo-1,6-dihydrouracil (2a) which decomposes in alkaline solution to yield also 6-cyanouracil (3a) and nitrogen. In a similar way 6-cyano-1,3-dimethyluracil (3b) is obtained from the 5-diazo-1,3-dimethyluracil derivative 1b via the 6-cyanoadduct 2b. Monosubstituted diazenes are suggested as labile intermediates in this reaction.
    Notes: Einwirkung von wäßriger Kaliumcyanidlösung auf das 5-Diazouracil-Methanoladdukt 1a führt unter Stickstoffabspaltung zum 6-Cyanuracil (3a). Mit wäßrigem Cyanwasserstoff ergibt 1a zu-nächst 6-Cyan-5-diazo-1,6-dihydrouracil (2a), das in wäßrig-alkalischem Medium ebenfalls in 3a übergeht. In gleicher Weise erhält man aus dem 5-Diazo-1,3-dimethyluracilderivat 1b über das 6-Cyanaddukt 2b 6-Cyan-1,3-dimethyluracil (3b). Als instabile Zwischenprodukte dieser Reaktion werden monosubstituierte Diazene vorgeschlagen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119810813
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    Mono-, Bis- und Trishydrazo- und -azoverbindungen der Tricyanbenzolreihe, I. Darstellung und Eigenschaften der Titelverbindungen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1586-1597 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mono-, Bis- and Trishydrazo, and -azo Compounds in the Tricyanobenzene Series, I. - Synthesis and Properties of the Title CompoundsIn 2-bromo-1,3,5-benzenetricarbonitrile (3) and chlorobenzenepentacarbonitrile (4) the halogen atoms can easily be substituted for phenylhydrazine. Also in 2,4,6-trichloro-1,3,5-benzenetri-carbonitrile (1) and 2,4,6-trifluoro-1,3,5-benzenetricarbonitrile (2) one or two halogen atoms can easily be replaced with phenylhydrazine forming the monohydrazo compounds 5a, b and the bishydrazo compounds 6a, b. The substitution of all three halogen atoms by phenylhydrazine is only possible under drastic conditions (pressure) using the fluorine compound 2. In 6a the remaining fluorine atom can also be replaced with phenolate ions, alkyl-(aryl-)thiolate ions or amines. Oxidation of the hydrazo derivatives 5a - d, 6a - f, and 7 with lead dioxide gives the azo compounds 8a - d, 9a - f, and 10. The chemical and spectroscopical properties of the hydrazo and azo compounds are described.
    Notes: Die Halogenatome in 2-Brom-1,3,5-benzoltricarbonitril (3) und Chlorbenzolpentacarbonitril (4) lassen sich glatt durch Phenylhydrazin substituieren. Auch in 2,4,6-Trichlor-1,3,5-benzoltricarbonitril (1) und 2,4,6-Trifluor-1,3,5-benzoltricarbonitril (2) können ein oder zwei Halogenatome leicht durch Phenylhydrazin substituiert werden, wobei die Monohydrazoverbindungen 5a, b sowie die Bishydrazoverbindungen 6a, b gebildet werden. Die Substitution aller drei Halogenatome durch Phenylhydrazin ist nur im Fall der Fluorverbindung 2 möglich und auch dann nur unter drastischen Bedingungen (Druck). In 6a kann das verbleibende Fluoratom auch durch Phenolat-Ionen, Alkyl-(Aryl-)thiolat-Ionen oder durch Amine nucleophil substituiert werden. Die Oxidation der Hydrazoderivate 5a - d, 6a - f und 7 mit Bleidioxid ergibt die entsprechenden Azoverbindungen 8a - d, 9a - f und 10. Die chemischen und spektroskopischen Eigenschaften der Hydrazo- und Azoverbindungen werden beschrieben.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119810908
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  • 130
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    Synthese und Ligandeneigenschaften der 2,3,11,12-Tetraphenyl-[18]krone-6-Diastereomeren (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1774-1784 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Ligand Properties of the 2,3,11,12-Tetraphenyl[18]crown-6 DiastereomersThe synthesis and the assignment of the complete set of diastereomers 2a -e of 2,3,11,12-tetraphenyl[18]crown-6 are described. The trans-anti-trans isomer 2d is identified by chiral interaction of optically active 1-phenylethylammonium hydrobromides with the racemic crown ether shown by NMR spectroscopy. Complex association constants of the new crown ethers with sodium, potassium, and ammonium picrates are discussed in terms of the geometry of the diastereomers.
    Notes: Die Synthese und die Zuordnung sämtlicher Diastereomeren 2a -e von 2,3,11,12-Tetraphenyl[18]krone-6 werden beschrieben. Die Identifizierung des trans-anti-trans-Isomeren 2d erfolgt durch NMR-spektroskopisch gezeigte chirale Wechselwirkung von optisch aktiven 1-Phenylethyl-amin-hydrobromiden mit dem racemischen Kronenether. Die Komplexassoziationskonstanten der neuen Kronenether mit Natrium-, Kalium- und Ammoniumpikraten werden im Zusammenhang mit der Geometrie der Diastereomeren diskutiert.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119811006
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  • 131
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    The Preparation and Some Reactions of Unsymmetrical Acyl Thioacyl Sulfides (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1798-1811 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung und einige Reaktionen von unsymmetrischen Acyl(thioacyl)sulfidenDurch Umsetzung von Piperidinium- oder Natrium-dithiocarboxylaten mit Acylchloriden oder durch Entschwefelung von Acyl(thioacyl)disulfiden mit Triphenylphosphan wurden einige un-symmetrische Acyl(thioacyl)sulfide [RC(S)S(O)CR'] dargestellt und charakterisiert. Die tiefblauen Öle oder hellgrünen Kristalle sind thermisch labil und feuchtigkeitsempfindlich. Die n →π-Übergänge der Thiocarbonylgruppe in 1 treten bei höheren Wellenlängen auf als die der entsprechenden symmetrischen Bis(thioacyl)sulfide [RC(S)S(S)CR']. Einige Reaktionen mit Nucleophilen werden diskutiert. Die Umwandlung von unsymmetrischen Acyl(thioacyl)sulfiden in symmetrische Bis(thioacyl)disulfide erfolgt in Gegenwart von Basen wie Lithium-ethanthiolat mit guten Ausbeuten.
    Notes: A number of unsymmetrical acyl thioacyl sulfides [RC(S)S(O)CR'] have been prepared and characterized by the reaction of piperidinium or sodium dithiocarboxylates with acyl chlorides or by desulfurization reaction of acyl thioacyl disulfides with triphenylphosphine. They are deep blue oils or light green crystals and very unstable thermally and for moisture. The n →π transitions of the thiocarbonyl group of 1 appear in higher wave length region than those of the corresponding symmetrical bis(thioacyl) sulfides [RC(S)S(S)CR']. Some reactions with nucleophiles are discussed. It was found that the symmetricallization reaction of these unsymmetrical acyl thioacyl sulfides occurs in the presence of base such as lithium ethanethiolate to give the symmetrical bis(thioacyl) disulfides in fair yield.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119811008
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  • 132
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    Darstellung und Röntgenstrukturanalyse von Bicyclo-[4.2.1]non-3-en-2-on-Derivaten (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1826-1837 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and X-Ray Structure Determination of Bicyclo[4.2.1]non-3-ene-2-one DerivativesMethyl 4-chloro- and methyl 4-bromo-5-oxobicyclo[4.2.1]non-3-ene-1-carboxylate (2) and (3), respectively, 3-bromo-4-chlorobicyclo[4.2.1]non-3-ene-2-one (4), and methyl 5-oxobicyclo[4.2.1]-non-3-ene-1-carboxylate (5) have been prepared from the corresponding bicyclo[3.2.1]oct-2-ene derivatives via the dihalocarbene adducts, and X-ray structure analysis was carried out. In all cases a half-chair conformation was found for the five-membered rings whereas the seven-membered rings possess a twist-chair conformation. The enone system is almost planar in 3 and 5 but somewhat distorted in 2 and 4.
    Notes: 4-Chlor- und 4-Brom-5-oxobicyclo[4.2.1]non-3-en-1-carbonsäure-methylester (2) bzw. (3), 3-Brom-4-chlorbicyclo[4.2.1]non-3-en-2-on (4) und 5-Oxobicyclo[4.2.1]non-3-en-1-carbonsäure-methylester (5) wurden aus den entsprechenden Bicyclo[3.2.1]oct-2-en-Derivaten über die Dihalogencarbenaddukte dargestellt und einer Röntgenstrukturanalyse unterworfen. In allen Fällen liegt der Fünfring in einer Halbsesselkonformation vor, der Siebenring nimmt eine Twist-Sesselkonformation ein. In 3 und 5 ist das Enon-System annähernd planar, in 2 und 4 etwas verdrillt.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119811010
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  • 133
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    Reaktionen CH-aktiver Verbindungen mit Aziden, XXX. Synthese von (Diazomethyl)phosphoniumsalzen durch Diazogruppen-Übertragung (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1865-1873 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of CH-Active Compounds with Azides, XXX1).  -  Synthesis of (Diazomethyl)-phosphonium Salts by Diazo Group TransferDiazo group transfer onto the (acylmethyl)triphenylphosphonium salts 10a - j with the azidinium salt 2 yields the α-diazophosphonium salts 12a - j besides the 2-aminobenzthiazolium salt 13; analogously, starting with 15, the diazo compounds 16 or 17 are formed, depending on the molar ratio of the methylene compound and 2.  -  By photolysis in methanol 12a is transformed into the O/H-insertion compound 20; the decomposition of 12j in acetic acid/p-toluenesulfonic acid leads to 21. The reaction of 12b with 2 mol triphenylphosphane yields the bis(phosphonium) salt 23.
    Notes: Diazogruppen-Übertragung auf die (Acylmethyl)triphenylphosphoniumsalze 10a - j mit dem Azidiniumsalz 2 liefert die α-Diazophosphoniumsalze 12a - j neben dem 2-Aminobenzthiazoliumsalz 13; aus 15 entstehen die Diazoverbindungen 16 oder 17, je nach Molverhältnis von 15 zu 2.  -  Durch Photolyse in Methanol wird 12a in die O/H-Insertionsverbindung 20 umgewandelt; die Zersetzung von 12j in Essigsäure/p-Toluolsulfonsäure führt zu 21. Die Umsetzung von 12b mit 2 mol Triphenylphosphan liefert das Bis(phosphonium)salz 23.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198119811013
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    Polyhydroxyamine via Diensynthese mit Nitrosoverbindungen, VIII. Darstellung von Diaminoderivaten über Epoxide (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1874-1879 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Poylhydroxyamino Compounds via Diene Synthesis with Nitroso Compounds, VIII1).  -  Preparation of Diamino Derivatives via EpoxidesThe epoxidation of the aminocyclohexenols 1 proceeds specifically with syn-attack and formation of the epoxides 2. Reactions of 2 with ammonia or dimethylamine leads to the inosdiamines 3 or 4, respectively.
    Notes: Die Epoxidierung der Aminocyclohexenole 1 erfolgt spezifisch unter syn-Angriff, es werden die Epoxide 2 gebildet. Umsetzung von 2 mit Ammoniak oder Dimethylamin führt zu Inosdiaminderivaten 3 bzw. 4.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811014
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  • 135
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    Helicid, ein β-Allopyranosid aus Helicia erratica Hook (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1893-1895 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Helicid, a β-Allopyranoside from Helicia erratica HookHelicid (1), C13H16O7, was isolated from the seed of Helicia erratica Hook (Proteaceae). Its constitution and configuration was determined by proton and carbon-13 NMR spectroscopy to be 4-formylphenyl β-allopyranoside. Thus, acidic hydrolysis of helicid yields 4-hydroxybenzal-dehyde and allose.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198119811017
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    Notiz zur Phototropie des ChinaldinrotsHerrn Professor Dr. L. Horner zum 70. Geburtstag gewidmet. (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1896-1898 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Phototropic Reaction of Quinaldine RedContrary to the literature quinaldine red shows an irreversible photochemical reaction in halogenated solvents.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119811018
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  • 137
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    Masthead (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811101
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  • 138
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    Peptidkonformationen, XIII. cyclo-Enkephaline  -  Synthese und Konformationsstudien (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2028-2044 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Peptide Conformations, XIII1).  -  cyclo-Enkephalin  -  Synthesis and Conformational StudiesThe cyclic enkephalins cyclo(-Tyr1-Gly2-Gly3-Phe4-Xxx5-) with Xxx = Leu (c 1) and Xxx = Met (c 2) were synthesized and investigated in DMSO solution by 1H-NMR spectroscopy. Evaluation of the temperature and solvent dependence of the NH chemical shifts as well as coupling constants and intramolecular NOE effects leads to a predominant conformation containing two γ-turns (Gly3-CO←HN-Xxx5; Tyr1-CO←HN-Gly3. The same conformation has been found in cyclo(-Phe3Gly2-) (3). Side chain conformations of the aromatic amino acids are shortly discussed. Comparison of these results with those of the zwitterionic enkephalins 1 and 2 in DMSO suggests a possible γ,γ-conformation for the latter as well, instead of the previously assumed conformation with only one β-turn. Low solubilities of c 1 and c 2 prevented testing the biological activity.
    Notes: Die cyclischen Enkephaline cyclo(-Tyr1-Gly2-Gly3-Phe4-Xxx5-) mit Xxx = Leu (c 1) und Xxx = Met (c 2) wurden synthetisiert und 1H-NMR-spektroskopisch in DMSO-Lösung untersucht. Wie die Temperatur- und Lösungsmittelabhängigkeit der NH-Signale, die Kopplungskonstanten und die intramolekularen NOE-Effekte zeigen, nehmen beide Peptide eine Konformation mit zwei γ-Schleifen (Gly3-CO←HN-Xxx5; Tyr1-CO←HN-Gly3) ein, die auch für cyclo(-Phe3Gly2-) (3) gefunden worden ist. Die Seitenkettenkonformation der aromatischen Aminosäuren wird kurz diskutiert. Aus dem Vergleich dieser Ergebnisse mit denen der zwitterionische Enkephaline 1 und 2 in DMSO wird für die linearen Verbindungen ebenfalls eine γ,γ-Konformation in Gegensatz zu der früher angenommenen Konformation mit einer β-Schleife für möglich gehalten. Die geringen Löslichkeiten verhinderten Tests der biologischen Aktivität von c 1 und c 2.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119811111
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    Note on the Unusual Reduction of 9,10-Anthraquinone Monooxime to 9,10-Anthraquinone Monoimine with Alkali Metal Hydrides (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2085-2086 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811117
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  • 140
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    Notiz zur Darstellung partiell hydrierter 5-Hydroxy-1,7-naphthyridin-Derivate (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2087-2089 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Synthesis of Partially Hydrogenated 5-Hydroxy-1,7-naphthyridine DerivativesThe preparation of 5,6,7,8-tetrahydro-1,7-naphthyridine-5-ol (5) and of 1,2,3,4-tetrahydro-1,7-naphthyridine-5-ol (6) from ethyl 7-benzyl-5-oxo-5,6,7,8-tetrahydro-1,7-naphthyridine-6-carboxylate (1) is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811118
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  • 141
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    Pheromone XXXIV. Synthese konjugiert-ungesättigter Lepidopterenpheromone und Analoga (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2117-2138 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pheromones XXXIV.  -  Synthesis of Conjugated-Unsaturated Lepidoptera Pheromones and AnaloguesConjugated-unsaturated alkadienyl acetates, alkadienols, and alkadienals  -  known as sex pheromones of female butterflies and moths  -  with varying positions and configurations of double bonds were synthesized using a “unitized construction principle”.
    Notes: Nach Art eines “Baukastensystems” werden konjugiert-ungesättigte Alkadienylacetate, Alkadienole und Alkadienale, wie sie als Sexualpheromone weiblicher Schmetterlinge bekannt sind, mit unterschiedlichen Positionen und Geometrien der Doppelbindungen synthetisiert.
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    URL: http://dx.doi.org/10.1002/jlac.198119811205
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    Di- und Polyaminozucker, XXV. Synthesen N-verknüpfter Saccharide  -  Reaktionen von Amino- mit Epoxyzuckern (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2139-2163 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Di- and Polyamino Sugars, XXV.  -  Syntheses of N-Connected Saccharides  -  Reactions of Amino with Epoxy SugarsSeveral diglycos-6-(3)-ylamines (secondary amines) and triglycos-6-(3)-ylamines (tertiary amines) were synthesized via ring opening of the 5,6-anhydro sugars 1 and 18 by 6-amino-6-deoxy-D-glucose, 3-amino-3-deoxy-D-glucose, and 3-amino-3-deoxy-D-altrose derivatives and could be obtained as the unblocked hydrochlorides. Furthermore, the reaction of these di- and triglycos-6-(3)-ylamines which have potential amino groups in form of the azido functions with another anhydro sugar led after hydrogenation to a number of pseudo tri-, tetra-, and pentasaccharides.
    Notes: Die 5,6-Anhydrozucker 1 und 18 wurden mit 6-Amino-6-desoxy-D-glucose-, 3-Amino-3-desoxy-D-glucose- und 3-Amino-3-desoxy-D-altrose-Derivaten unter Öffnung des Oxiranringes durch die Aminogruppen umgesetzt. Sowohl Diglycos-6-(3)-ylamine (sekundäre Amine) als auch Triglycos-6-(3)-ylamine (tertiäre Amine) wurden isoliert, derivatisiert und zu den freien Zuckern deblockiert. Darüber hinaus konnten diese Saccharide, die potentielle Aminogruppen in Form der Azidofunktion enthalten, nach Hydrierung erneut mit einem Anhydrozucker zur Reaktion gebracht werden. Auf diese Weise wurden aus drei, vier und fünf Zuckermolekülen aufgebaute Verbindungen synthetisiert.
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    URL: http://dx.doi.org/10.1002/jlac.198119811206
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    Cyclit-Reaktionen, V. Synthese von enantiomerenreinem Valienamin aus Quebrachit (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2180-2203 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclitol Reactions, V.  -  Synthesis of Enantiomerically Pure Valienamine from QuebrachitolAn enantioselective synthesis of Valienamine (86) from quebrachitol (L-2-O-methyl-chiro-inositol) (1) is described. Valienamine (86) is an unsaturated branched-chain aminocyclitol found in the central structural unit of the antidiabetic drug acarbose. Techniques for the introduction of side chains, azido groups, and double bonds into inositol systems are investigated. The methods developed in this connection are applied in the synthesis of valienamine.
    Notes: Die enantioselektive Synthese des Valienamins (86) aus Quebrachit (L-2-O-Methyl-chiro-inosit) (1) wird beschrieben. Valienamin (86) ist der zentrale Baustein des Antidiabetikums Acarbose. Die Möglichkeiten zur Einführung von Seitenketten und Azidogruppen sowie die Herstellung von Doppelbindungen in Inositsystemen werden untersucht. Die hierbei erprobten Reaktionen finden bei der Valienaminsynthese Anwendung.
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    URL: http://dx.doi.org/10.1002/jlac.198119811208
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    Untersuchungen über Derivate der D-Threose und zur Darstellung der Seitenkette von Olivin (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2216-2227 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on D-Threose Derivatives and on the Preparation of the Olivin Side ChainOxidative cleavage of the D-arabinitol derivative 3 yields the dimer 5 of benzylidene D-threose. In pyridine solution D-threose (11), obtained by acid hydrolysis, predominantly represents a mixture of the anomeric furanoses 7 and 12. By either kinetic or thermodynamic isopropylidenation of the trimethylene dithioacetal 9 preparation of the terminal or the non-terminal dioxolane 14 or 16, respectively, is achieved selectively. Starting with 16 several steps lead to the crystalline 4-deoxy-D-threose trimethylene dithioacetal (25), by metallation of which the formation of a trianion could not be demonstrated. However, both the diastereomeric model compounds 28 and 30 of the olivin side chain were prepared via dimetallation of 14.
    Notes: Durch oxidative Spaltung des D-Arabitderivats 3 wird das Dimere 5 der Benzyliden-D-threose erhalten. Die daraus durch saure Hydrolyse gewonnene D-Threose (11) liegt in Pyridinlösung vorwiegend als Gemisch der anomeren Furanosen 7 und 12 vor. Nach Darstellung des Trimethylendithioacetals 9 kann dessen selektive Isopropylidenierung entweder kinetisch zum endständigen oder thermodynamisch zum mittelständigen Dioxolanderivat 14 bzw. 16 gesteuert werden, Aus 16 wird über mehrere Stufen 4-Desoxy-D-threose-trimethylendithioacetal (25) kristallin erhalten, dessen Metallierung zum Trianion nicht nachzuweisen war. Dagegen gelingt die Dimetallierung von 14, aus dem die diastereomeren Modellverbindungen 28 und 30 der Olivinseitenkette dargestellt werden konnten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811210
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    Thiocarbonyl-Olefinierung, IV. Darstellung von β-Aminosäuren aus N-(Acetyl)thioamiden; Totalsynthese der Iturinsäure (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2258-2265 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thiocarbonyl Olefination, IV.  -  Preparation of β-Amino Acids from N-(Acetyl)thioamides; Total Synthesis of Iturinic AcidA new method for the synthesis of β-amino acids is described whose key step consists in the regioselective thiocarbonyl olefination of N-(acetyl)thioamides with methyl (triphenylphosphoranylidene)acetate. By this procedure, a straightforward synthesis of iturinic acid has been carried out for the first time.
    Notes: Eine neue präparative Methode für β-Aminosäuren, deren Schlüsselreaktion die regioselektive Thiocarbonyl-Olefinierung von N-(Acetyl)thioamiden mit (Triphenylphosphoranyliden)essigsäuremethylester darstellt, wird beschrieben. Mit Hilfe des erläuterten Verfahrens wurde Iturinsäure erstmalig synthetisiert.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/jlac.198119811213
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    Synthese und biologische Aktivitäten von (+)- und (-)-Multifiden (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2266-2271 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Biological Activities of (+)- and (-)-Multifidene(+)-Multifiden 1, the specific messenger for androgametes of the phaeophyte Cutleria multifida, is about 100 times more active than the (-)-enantiomer of 1. Both enantiomers are conveniently prepared by chromatographic resolution of the diastereomeric carbamates 5a/b or 5c/d which give easy access to (+)- and (-)-1 by only a few subsequent steps.
    Notes: (+)-Multifiden 1, der spezifische Signalstoff für Androgameten der Braunalge Cutleria multifida, ist etwa 100fach wirksamer als das (-)-Enantiomere von 1. Die optische Reindarstellung beider Antipoden gelingt durch chromatographische Trennung der diastereomeren Carbamate 5a/b und 5c/d, aus denen (+)-und (-)-1 in nur wenigen Schritten zugänglich sind.
    Additional Material: 1 Ill.
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    Synthetische Anthracyclinone, XVIII. Synthese des 13-Desoxo-6-desoxydaunomycinons und des β1-Citromycinons (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2285-2297 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthetic Anthracyclinones, XVIII.  -  Synthesis of 13-Deoxo-6-deoxydaunomycinone and β1-Citromycinone8-O-Methylchrysophanol 5b is obtained via regioselective diene reaction of juglone (2) and 3-methyl-1-trimethylsiloxy-1,3-butadiene (3), methylation of the adduct 4a, cleavage of the trimethylsilylether 4c, and pyridinium chlorochromate (PCC) oxidation of 4d to 5b. A substituent at C-2 can be introduced by hydroxymethylation of 5b to 6a and chain elongation to yield the ketone 8a. The protected monobromide 8f cyclises by treatment with magnesium to 9a which is stereoselectively hydroxylated at C-10 to give the natural product 9b. The trans-7,8-diole 13c is available by epoxidation of the olefine 12, opening of the epoxide 13a with sodium acetate, and saponification of 13b.
    Notes: Der 8-O-Methylether 5b des Chrysophanols wird über eine regioselektive Dienreaktion von Juglon (2) mit 3-Methyl-1-trimethylsiloxy-1,3-butadien (3), Methylierung des Addukts 4a, Spaltung des Trimethylsilylethers 4c und Pyridinium-chlorochromat-(PCC-)Oxidation von 4d zu 5b erhalten. Ein Substituent an C-2 kann durch Hydroxymethylierung von 5b zu 6a gefolgt von Kettenverlängerung zum Keton 8a eingeführt werden. Das geschützte Monobromid 8f wird durch Behandlung mit Magnesium zu 9a cyclisiert und stereoselektiv an C-10 zum Naturstoff 9b hydroxyliert. Das trans-7,8-Diol 13c ist über Epoxidierung des Olefins 12, Öffnung des Epoxids 13a mit Natriumacetat und Verseifung von 13b zugänglich.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811216
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    Glycosylhydrazine, 6. Synthese von Pyrazol-, Pyrazolo[3,4-d]pyrimidin-und 1H-1,2,4-Triazolgluconucleosiden aus Glucosehydrazonen (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2309-2317 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glucosylhydrazines, 6.  -  Synthesis of Pyrazole, Pyrazolo[3,4-d]pyrimidine, and 1H-1,2,4-Triazole Gluconucleosides from Glucose HydrazonesThe β-linked pyrazole gluconucleosides 6b, 12b, 13b, and 14b were obtained regio- and diastereoselectively from 2,3,4,6-tetra-O-benzyl-D-glucose hydrazone (5b) and acetylacetone, (ethoxymethylene)malondinitrile, (ethoxymethylene)cyanoacetate, and (aminomethylene)cyanoacetamide, respectively, in a one-pot reaction after two ring closures. 12b and 13b were transformed into the unprotected pyrazolo[3,4-d]pyrimidine gluconucleosides 15a and 16a (analogues of adenosine and inosine). Similarly from 5b and N-(ethoxymethylene)oxalate monoamide the β-linked glucopyranosyl-1 H-1,2,4-triazole-5-carboxylate 20 and from 5b and activated formic acid derivatives the parent triazole derivative 22 were obtained.
    Notes: 2,3,4,6-Tetra-O-benzyl-D-glucosehydrazon (5b) lieferte mit Acetylaceton, (Ethoxymethylen)malodinitril, (Ethoxymethylen)cyanessigester und (Aminomethylen)cyanacetamid in einem Reaktionsschritt nach zweifachem Ringschluß regio- und diastereoselektiv die β-verknüpften Pyrazolgluconucleoside 6b, 12b, 13b und 14b. Die Nucleoside 12b und 13b wurden in die ungeschützten Pyrazolo[3,4-d]pyrimidingluconucleoside 15a und 16a (Analoge des Adenosins bzw. Inosins) übergeführt. Entsprechend wurde aus 5b und N-(Ethoxymethylen)oxalsäureestermonoamid in einem Schritt der β-verknüpfte Glucopyranosyl-1 H-1,2,4-triazol-5-carbonsäureester 20 und mit aktvierten Ameisensäurederivaten das unsubstituierte 1H-1,2,4-Triazolderivat 22 erhalten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811218
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    The Preferred Conformations of Glycosylalditols (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2372-2383 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bevorzugte Konformationen von GlycosylalditenDie Kristallstrukturanalyse von 6-O-(α-D-Glucopyranosyl)-D-glucit (Isomaltit 1) zeigt die Glucose in normaler 4C1-Sesselkonformation mit einer abgewinkelten Glucitkette glycosidisch verknüpft, wobei der Mittelteil eine planare, in den pyranoiden Ring hineinreichende Zickzack-Kette bildet. Die vergleichende Bewertung der Konformations-Charakteristika von 1, dem D-Mannit-Analogen 2 sowie von (1 → 4)-verknüpften Analogen erlaubt  -  in Verbindung mit Jeffreys Alditol-Regeln und den Prinzipien des exo-anomeren Effekts  -  zuverlässige Voraussagen zur Konformation von Glycosylalditen im allgemeinen.
    Notes: Crystal structure analysis shows 6-O-(α-D-glucopyranosyl)-D-glucitol (isomaltitol 1) to have a bent glucitol chain linked to glucose in normal 4C1-chair form, the middle section forming a planar zigzag chain that extends into the pyranoid ring. Comparative assessment of the conformational features of 1, its D-mannitol analogue 2, and of some (1 → 4)-linked analogues allows  -  in combination with Jeffrey's alditol rules and the exo-anomeric effect principles  -  to predict with significant confidence the preferred conformations of glycosylalditols in general.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jlac.198119811221
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    Stereoselective Syntheses of (±)-epi-β-Santalene and (±)-epi-β-Santalol (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 25-32 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective syntheses of (±)-epi-β-santalene (1) and (±)-epi-β-santalol (2), minor constituents of East Indian sandalwood oil, are described. The starting material for both syntheses is the tricyclic hemiacetal 4, readily accessible in two steps from norbornene.
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    Ladroside (= 6′-Caffeoyl-mussaenoside), a New Iridoid Glucoside from Veronica officinalis L. (Scrophulariaceae) and the elucidation of the absolute configuration at C(8) of mussaenosidePresented by O. St. and F. Ü. A.-Y. at the 25. Jubiläumsvortragstagung der Gesellschaft für Arzneipflanzenforschung, Zürich, Switzerland, September 12--16, 1977; s.[1a]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 16-24 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new iridoid glucoside, named ladroside, together with mussaenoside (1) [2], has been isolated from Veronica officinalis L. The structure of ladroside (4) and the identity of mussaenoside have been established by spectral analysis. Additionally, the absolute configuration at C(8) carrying the tertiary hydroxyl group has been established by chemical evidence.
    Additional Material: 2 Ill.
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    Azimine IV. Kinetik und Mechanismus der thermischen Stereoisomerisierung von 2,3-Diaryl-1-phthalimido-aziminenAzimine III: s. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 38-48 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Azimines IV. Kinetics and Mechanism of the Thermal Stereoisomerization of 2,3-Diaryl-1-phthalimido-azimines1)Mixtures of (1E, 2Z)- and (1Z, 2E)-2-phenyl-1-phthalimido-3-p-tolyl-azimine (3a and 3b, resp.) and (1E, 2Z)- and (1Z, 2E)-3-phenyl-1-phthalimido-2-p-tolylazimine (4a and 4b, resp.) were obtained by the addition of oxidatively generated phthalimido-nitrene (6) to (E)- and (Z)-4-methyl-azobenzene (7a and 7b, resp.). Whereas complete separation of the 4 isomers 3a, 3b, 4a and 4b was not possible, partial separation by chromatography and crystallization led to 5 differently composed mixtures of azimine isomers. The spectroscopic properties of these mixtures (UV., 1H-NMR.) were used to determine the ratios of isomers in the mixtures, and served as a tool for the assignment of constitution and configuration to those isomers which were dominant in each of these mixtures, respectively.Investigation of the isomerization of the azimines 3a, 3b, 4a and 4b within the 5 mixtures at various concentrations by 1H-NMR.-spectroscopy at room temperature revealed that only stereoisomers are interconverted (3a ⇄ 3b; 4a ⇄ 4b) and that the (1E, 2Z) ⇄ (1Z, 2E) stereoisomerization is a unimolecular reaction. These observations exclude an isomerization mechanism via an intermediate 1-phthalimido-triaziridine (2) or via dimerization of 1-phthalimido-azimines (1), respectively. The 3-p-tolyl substituted stereoisomers 3a and 3b isomerized slightly slower than the 3-phenyl substituted ones 4a and 4b, an effect which is consistent with the assumption that the rate determining step of the interconversion of (1E, 2Z)- and (1Z, 2E)-1-phthalimido-azimines (1a ⇄ 1b) is the stereoisomerization of the stereogenic center at N(2), N(3), either by inversion of N(3) or by rotation around the N(2), N(3) bond. The total isomerization process is assumed to occur via the thermodynamically less stable (1Z, 2Z)- and (1E, 2E)-isomers 1c and 1d, respectively, as intermediates in undetectably low concentrations which stay in rapidly established equilibria with the observed, thermodynamically more stable (1E, 2Z)- and (1Z, 2E)-isomers 1a and 1b, respectively.At higher temperatures, the azimines 3 and 4 are transformed into N-phenyl-N,N′-phthaloyl-N′-p-tolyl-hydrazine (8) with loss of nitrogen.
    Additional Material: 3 Tab.
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    Euphroside, A New Iridoid Glucoside from Euphrasia salisburgensis HOPPEPart 1 in the series ‘Glycosides of Euphrasia species’.See [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 78-81 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five iridoid glucosides have been isolated from the whole plant of Euphrasia salisburgensis. The structure of the new compound, named euphroside, and the identity of the others have been established by chemical transformations and spectral data.
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    Metallic Conductivity in Metal Tetraaza [14]Annulene Iodides: The Crystal Structures of Dihydrodibenzo-[b, i]-1, 4, 8, 11-tetraazacyclotetradecinenickel and -palladium Iodides (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 82-89 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Single crystals of dihydrodibenzo[b, i]-1, 4, 8, 11-tetraazacyclotetradecinenickel iodide show metallic conductivity between room temperature and approx. 110 K. The crystals are orthorhombic, space group Ibam with four formula units per cell of the following dimensions: a = 20.245, b = 13.416, c = 6.418 Å. The analogous palladium complex is isomorphous, the cell constants being a = 20.452, b = 13.430 and c = 6.499 Å. A number of other partially oxidized metal tetraaza [14]annulenes also show electrical conductivity.
    Additional Material: 4 Ill.
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    Some Comments on the Conformations of Methyl Phenyl Sulfides, Sulfoxides and Sulfones (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 97-112 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-NMR. and He (Iα) photoelectron spectra of alkyl phenyl sulfides, sulfoxides and sulfones have been used to probe how their conformations depend on the size of the alkyl groups R. The results are interpreted to indicate that in the sulfides the S, R-bond is twisted out of the planar conformation with increasing size of the alkyl group, whereas in the sulfoxides and sulfones the preferred conformation with the S, R-bond perpendicular to the phenyl group plane seems to be independent of the size of R. These conclusions are in agreement with previous work on the alkyl phenyl sulfides and provide strong support for previous conjectures concerning the preferred conformations of alkyl phenyl sulfoxides and sulfones.
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    Hindered Nucleophilic Displacement (SN 2) Reactions of 2exo- and 2endo- Norbornyl Derivatives. NorbornaneAccording to the IUPAC nomenclature ‘norbornane’ is now called ‘8,9,10-trinorbornane’.) Series 4 (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 153-160 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of 2exo- and 2endo-norbornyl bromide (1e and 2e, respectively) in 90% ethanol with a large excess of potassium hydroxide, and of 2exo-norbornyl p-toluenesulfonate (1g) with excess sodium thiophenolate in methyl cellosolve, have been studied. They obey the first order rate law and are zero order with respect to the base-nucleophile. However, the ratio of 1,2- and 1,3-elimination to exo-substitution products depends strongly on the base-nucleophile concentration. Ion pair intermediates are indicated. The extreme inertness of 2-norbornyl derivatives in displacement reactions is due to severe steric hindrance of rearside nucleophilic attack, a feature they have in common with other bi- and tricyclic molecules bearing nucleofugal groups adjacent to one or two bridgehead atoms.
    Additional Material: 4 Tab.
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    Electronic Absorption and Emission Spectra of 1, 3-DiaryltriazenesPresented at 175th National Meeting of the American Chemical Society, Anaheim, California, March 13-17, 1978. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 171-175 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Pariser-Parr-Pople (PPP) type LCI-SCF-MO calculations were used to study the models of 1, 3-diphenyltriazene (1), 1, 3-bis(3-pyridyl)triazene (2), 1, 3-bis (2, 4-dichlorophenyl)triazene (3), and 1, 3-bis (4-ethoxycarbonyl)triazene (4). The results of the calculations were compared with the experimental electronic absorption and emission (fluorescence, phosphorescence) spectra of these compounds.
    Additional Material: 1 Ill.
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    A Stereoselective Approach to the Spiro [4, 5]decane System via Intramolecular Photocycloaddition and Reductive Fragmentation. Preliminary communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 186-187 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photoaddition 6→7, followed by a reductive cleavage of the →-chlorocyclobutylketone 7, gave the stereochemically pure spiro [4,5]decane 8.
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    New Dienophiles: 1-Acetylvinyl Arenecarboxylates. Reactivity toward cyclopentadiene and exocyclic dienes (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 188-197 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparations of 1-acetylvinyl arenecarboxylates H2C=C(COCH3)OCOR with R = phenyl, p-nitrophenyl, 2,4-dinitrophenyl, α- and β-naphthyl are described (3). The Diels-Alder reactivity of these dienophiles toward cyclopentadiene is evaluated and compared with that of methyl vinylketone, 3-trimethylsilyloxy-, 3-ethoxy- and 3-acetoxy-3-buten-2-ones. The stereoselectivity of the cycloadditions of these dienophiles with 2,3,5,6-tetramethylidene-7-oxanorbornane (1) and 5,8-dimethoxy-1,4-epoxy-2,3-dimethylidene-1,2,3,4-tetrahydroanthracene (2) is studied. In principle, the dienophiles 3 allow direct functionalization of the position C(9) of the A-ring of daunomycinone analogs by Diels-Alder additions to exocyclic dienes such as 1 and 2.
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    URL: http://dx.doi.org/10.1002/hlca.19810640121
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    Photochemische Reaktionen. 117. Mitteilung [1] Zur Photochemie von 5,6-EpoxydienenTeil III; bzgl. Teil II s. [2]. und konjugierten 5,6-EpoxytrienenVgl. vorläufige Mitt. [3]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 198-214 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemistry of 5,6-Epoxydienes and of Conjugated 5,6-EpoxytrienesOn singulet excitation (δ = 254 nm) the 5,6-epoxydiene 6 and the conjugated 5,6-epoxytrienes 7 and 8 exclusively give products arising from cleavage of the C, C-bond of the oxirane (cf. 6→9, 10, 11; 7→ (E)-15, 16, 17; 8→ 18 (A+B), 19 (A+B), 20, 21). The dihydrofuran compounds 11 and (E/Z)-15 are formed by cyclization of a ketonium-ylide a and d, respectively. Photolysis of a gives the carbene b which yields the cyclopropene 9, whereas d forms photochemically the carbenes f and g which yield the methano compounds 16 and 17. The isomeric cyclopropene derivatives 20 and 21 are products of the intermediates h and i, respectively, which are formed by photolysis of the ylide e. The cyclopropene 21 isomerizes by intramolecular cycloadditions to 18 (A+B) and 19 (A+B). - On triplet excitation (λ≥LD nm; 280 nm; acetone) 6 undergoes cleavage of the C(5), O-bond and isomerizes to 12 and 14. However, 7 is converted by cleavage of the C, C-bond of the oxirane to yield 15. On treatment with BF3O(C2H5)2 6 gives 14, whereas 7 yields 22, and 8 forms 23 and 24.
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    Approaches to the Synthesis of Cytochalasans. Part 3Part 2: s. [1].. Synthesis of a substituted tetrahydroisoindolinone moiety possessing the same relative configuration as proxiphomin (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 235-250 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The total synthesis of the tetrahydroisoindolinone moiety corresponding to proxiphomin (1) is described, bearing functional groups for the attachment of the macrocyclic ring. Knoevenagel-Cope condensation of racemic 2-(benzyloxycarbonyl-amino)-3-phenylpropanal (2) with methyl (4-methyl-2,4-hexadienyl) malonate (3) yielded a mixture of the (E)- and (Z)-olefins 4a and 4b, which upon heating underwent intramolecular Diels-Alder cyclization (cf. Scheme 1). From the resulting products the tetrahydroisoindoline derivative 6 was isolated. X-ray analysis of 6[5] revealed the same relative configurations at C(3), C(4), C(5) and C(8) as in 1, but not at C(9). Hydrolysis of 6 with KOH was accompanied by a change in configuration at C(9) yielding the hydroxy acid 14 which was converted into the hydroxy ester 11 (cf. Scheme 4). The presence of a cis-anellated lactam ring in 11 has been confirmed by X-ray analysis of its O-acetyl derivative 16 [5]. Ring closure of the hydroxy acid 14 gave the lactone 17, corresponding to the natural product 1 as to the configuration. The presence of the N-benzyloxycarbonyl group in lactone 6 has been shown to be essential for the above-mentioned ‘inversion’ at C(9), because no configurational change occurred with the N-unprotected lactone 8 when treated under the same conditions. The only product obtained was the hydroxy ester 10 possessing the same configuration at C(9) as 8. Along with stereochemical considerations, mechanistic aspects of the reactions are discussed.
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    The Configuration of Tricyclo [7.1.1.02,7]undecanes and the Stereochemistry of the Reduction of Tricyclone (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 161-170 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A full discussion of the configuration of tricyclo [7.1.1.02,7]undecanes related to cis-10, 10-dimethyltricyclo [7.1.1.02,7]undec-2-en-4-one (2), the Robinson annelation product from norpinone 1 and 3-buten-2-one is given, based on 360-MHz-NMR. spectra. Nuclear Overhauser effects confirm the cis configuration of 2, and show that the saturated ketone 10, obtained by catalytic hydrogenation, is also all-cis with the cyclohexanone ring in the boat conformation. The parent hydrocarbon, cis-10, 10-dimethyltricyclo[7.1.1.02,7]undecane is compared with one of the corresponding trans isomers prepared from pinocarvone (14). The stereochemistry of metal hydride reduction and Grignard reaction of 2 is examined.
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    Physico-Chemical Properties of Deuterated Compounds. 5th Communication4th Communication, see[1].. The isotope partition coefficient in cyclohexane hydrogen and cycloheptane/hydrogen mixtures (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 176-179 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The isotope partition coefficient α between cyclohexane, cycloheptane and hydrogen has been determined between 80 and 180° and pressures around 1 atm. The values decrease with increasing deuterium content y of the hydrogen and can be expressed by the simple equation Ina = Δ S/R + (ΔH + δ · y)/RT with an error of ±1%. However it was not possible to achieve good agreement with theoretical calculations using a unique average value for the partition function of the hydrocarbon.
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    Reduction of 2-Bromo-4, 4-dimethyl-2-cyclohexenone at Mercury. A study on inverted peaks in cyclic voltammetryReported at the 4th EUCHEM Conference on Organic Electrochemistry at Rodez (France), May 1980. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 180-185 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The parameters which influence the inverted wave appearing in the reverse (oxidation) sweep in the cyclic voltammogramme of the title compound 1 are discussed in detail. The inverted wave is due to the interaction of the reduction products of 1 with the electrode and the electrolyte (TBAFB). The key condition for the presence of the inverted peak is a slow scan rate on the reverse sweep, at least for the last 50 mV before the inversion of the current-potential curve.
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    Photochemische Reaktionen. 118. Mitteilung [1] Zur vinylogen β-Spaltung von Enonen. UV.-Bestrahlung von 4-(3',7',7'-Trimethyl-2'-oxabicyclo [3.2.0]hept-3'-en-1'-yl)but-3-en-2-on (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 215-223 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinylogous β-Cleavage of Enones: UV.-irradiation of 4-(3′,7′,7′-trimethyl-2′-oxabicyclo[3.2.0]hept-3′-ene-1′-yl)but-3-ene-2-onOn 1π,π*-excitation (λ = 254 nm) in acetonitrile (E/Z)-2 is converted into the isomers 4-9 and undergoes fragmentation yielding 10; in methanol (E/Z)-2 gives 7-10 and is transformed into 11 by incorporation of the solvent.On 1π,π*-excitation (λ λ≥347 nm; benzene-d6) (E)-2 is isomerized into (Z)-2, which is converted into the isomers 3 and 4 by further irradiation.1π,π*-Excitation (λ = 254 nm; acetonitrile) of 4 gives 6 and (E)-9, whereas UV.-irradiation (λ = 254 nm; acetonitrile-d3) of 5 yields (E)-7 and 8.On 1π,π*-excitation (λ = 254 nm; acetonitrile) of (E/Z)-12 the compounds (E)-14 and (E)-15 are obtained.
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    Dediazoniation of Arenediazonium Ions in Homogeneous Solutions. Part XVI. Kinetics and mechanisms of dediazoniation of p-chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions under nitrogen gasPart XV: s. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 513-528 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of reactions of p-chlorobenzenediazonium ions in aqueous buffer solutions (pH 9.0-10.6) under N2 (〈 5 ppb of O2) have been measured between 20 and 50°C. The formation of trans-diazotate is first-order with respect to the concentration of hydroxyl ions and to the equilibrium concentration of diazonium ions, if the diazonium ion⇄cis-diazotate equilibrium is considered as a fast prior equilibrium. This indicates that the p-chlorobenzenediazonium ion, in contrast to all previous investigations with the p-nitrobenzenediazonium ion and benzenediazonium ions carrying similar substituents with a -M effect, rearranges from the cis- to the trans-configuration as diazohydroxide and not as diazotate. The formation of trans-diazotate is catalyzed by carbonate and inhibited by hydrogen carbonate ions; mechanisms of these catalyses are discussed, and the solvent isotope effect KH2O/KD2O measured by an 1H-NMR. technique reported. The kinetics of the dediazoniations can be analyzed as a mixture of two reactions, a relatively fast first reaction, reaction A, which is responsible for about 5% of the total reaction, and a second reaction F. Both are first-order with respect to diazonium ion; reaction A is also first-order in hydroxyl ions. There are some indications that reaction A corresponds to the hydrolysis of the diazonium ion to give eventually amine and nitrite ions. Reaction F shows a complex dependence on hydroxyl ions; it is related to the homolytic dediazoniation.
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    Selectivities in the Reactions of Alkyl-, Aryl- and Heterosubstituted Organotitanium Compounds Preliminary Communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 357-361 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solutions of the title compounds R-Ti(OR′)3 (1) are generally available from organolithium (or magnesium) derivatives according to equation 1. It is shown (Table 1) that some heterosubstituted organotitanium compounds are more stable thermally than their lithium counterparts. The reagents 1 are highly selective carbonylophiles (Tables 1 and 2), their reactivity can be modified by variation of the R′O-group (Table 3) and with the chiral (S)-2-methyl-l-butoxy group an enantioselective addition can be achieved [equ. 2].
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    The Reaction of Pyruvic Acid with Amines and Aminoesters Reexamined. Preliminary communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 568-571 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenylglycine esters react with pyruvic acid to give α-methylsuccinic amides 9 instead of the expected Schiff bases 8, analogously to p-anisidine but unlike aniline.
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    Notizen zur Synthese sulfonierter Derivate von 5,6,7,8-Tetrahydro-1-naphthylamin und 5,6,7,8-Tetrahydro-2-naphthylamin (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 572-578 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Notes on the Synthesis of Sulfonated Derivatives of 5,6,7,8-Tetrahydro-1-naphthylamine and 5,6,7,8-Tetrahydro-2-naphthylamineSulfonation of 5,6,7,8-tetrahydro-1-naphthylamine (1) with sulfuric acid gave a mixture of 1-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (2), 4-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (13) and 4-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid (3). The same reaction with 5,6,7,8-tetrahydro-2-naphthylamine (20) yielded 3-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (21); formation of 2-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid (16) or of 3-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid (24) was not observed. Treatment of 4-bromo-5,6,7,8-tetrahydro-1-naphthylamine (4) or of its 4-chloro analogue 5 with amidosulfuric acid gave 1-amino-4-bromo-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (9) and its 4-chloro analogue 10, respectively, which were dehalogenated to 2. Preparations of 13 and 24 were achieved by sulfonation of 5-nitro-1,2,3,4-tetrahydronaphthalene (14) and 6-nitro-1,2,3,4-tetrahydronaphthalene (22) to 4-nitro-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (15) and 3-nitro-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid (23), respectively, followed by Béchamp reductions. The sulfonic acid 13 was also obtained by hydrogenolysis of 4-amino-1-bromo-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (11) or of its 1-chloro analogue 12; compounds 11 and 12 were synthesized from N-(4-bromo-5,6,7,8-tetrahydro-1-naphthyl)acetamide (7) and from its 4-chloro analogue 8, respectively, by sulfonation with oleum and subsequent hydrolysis. By ‘baking’ the hydrogensulfate salt of 1 or 20 compounds 3 and 21 were obtained, respectively. Synthesis of 16 was achieved by sulfur dioxide treatment of the diazonium chloride derived from 2-nitro-5,6,7,8-tetrahydro-1-naphthylamine (17) giving 2-nitro-5,6,7,8-tetrahydronaphthalene-1-sulfonyl chloride (18), followed by hydrolysis of 18 to the corresponding sulfonic acid 19 and final reduction.
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    Complexes of Lanthanoid Nitrates with 15-Crown-5 and 18-Crown-6 EthersPart 10 of the series «Complexes of Lanthanoid Salts with Macrocyclic Ligands». Part 9 [22].Abstracted in part from the Ph.D. Thesis of D.W. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 582-598 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes between the heavier lanthanoid nitrates Ln(NO3)3 and 15-crown-5 (1) and 18-crown-6 (2) ethers were isolated and characterized. Both 1:1 and 4:3 complexes are formed with each Ln(III) ion, except in the case of Gd and 2. The thermal transformation of the 1:1 complexes into the corresponding 4:3 complexes was studied by thermogravimetry and by DSC, X-ray and vibrational data provide information about the structure of these complexes. The interaction between Ln(III) ions and ligands 1 and 2 in non-aqueous solutions is discussed on the basis of conductometric, fluorescence, UV./VIS. and 1H-NMR. data. Only 1:1 complexes of 2 formed in solution and their formation constants range from logKf = 4.4 (Ln = La) to 2.4 (Ln = Yb); for Eu, Kf of the 15-crown-5 and 18-crown-6 ether complexes are of the same order of magnitude. For La, Pr, Nd, Eu, Yb, a variable temperature NMR. study gave some indications about the chemical exchanges in solution.The factors which determine the stoichiometry of the complexes are discussed.
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    Mitteilungen - Communications (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 620-621 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Dérivés de désoxy-hydroxylamino-sucres et radicaux libres diglycosylnitroxydes correspondantsRadicaux libres dérivés de sucres, IV; Communications I, II et III: resp. [1], [2] et [3].. Communication préliminaireUne communication plus détaillée paraîtra ultérieurement. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 610-616 
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    Notes: Deoxy-hydroxylamino-sugar Derivatives and Corresponding Diglycosylnitroxides RadicalsA number of sugar aldonitrones, including C,N-diglycosylnitrones, and ketonitrones have been treated with Grignard reagents or cyanide anion leading to the corresponding deoxy-hydroxylamino-sugars. On oxidation (air, H5IO6 or PbO2), these compounds gave the corresponding nitroxide radicals whose ESR. spectra are reported. Analogues of disaccharides, in which the interglycosidic O-bridge is replaced by a hydroxyimino group, have been obtained by reacting a partially blocked sugar bearing a free hemiacetal group either with a deoxy-hydroxylaminosugar or with hydroxylamine, followed by reaction with an aldehydosugar and a reducing agent (NaBH4). These reactions represents the key synthetic steps for the oligosaccharide-type synthesis of deoxy-hydroxyimino-oligosaccharides. Their oxidation yielded the corresponding nitroxide radicals whose ESR. spectra gave information on the conformation about the ‘interglycosidic’ bridge. This type of compounds should constitute useful spin markers for biological studies.
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    Natural Occurrence of Enantiomeric and meso-Astaxanthin. 5. Ex wild salmon (Salmo salar and Oncorhynchus) (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 449-457 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The configurational isomers of astaxanthin (3,3′-dihydroxy-β,β-carotene-4,4′-dione) from the flesh of salmon (Salmo salar and Oncorhynchus) caught at different places in Europe and Canada were isolated and analyzed as (-)-camphanic acid diesters by means of HPLC. The biological variation in the composition of the configurational isomers in seven fish was surprisingly similar: 78 to 85% of (3S, 3′S)-astaxanthin, 12 to 17% (3R, 3′R)-astaxanthin and 2 to 6% meso-astaxanthin.
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    Computer Assisted Structural Interpretation of Mass Spectral DataPart XXXVI of the series ‘Application of Artificial Intelligence for Chemical Inference’. For part XXXV see [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 458-470 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An interactive system of programs has been developed to assist in structure elucidation based on mass spectral data. The program relies on algorithms for generating all the structural isomers that constitute alternative explanations of the observed data and it associates relative plausibility values with the different isomers. The structure assembly part of the program allows for the use of overlapping substructural components, such as substructures inferred from the appearance of particular ion patterns in the spectrum of an unknown compound. Mass spectrum interpretation procedures used with this structure assembly process could exploit any form of spectrum-substructure correlation scheme. In this work, the emphasis has been on the use of detailed and class specific spectrum-substructure correlations. Applications of the program are illustrated by means of an example analysis of the mass spectra of a variety of marine sterols.
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    Selektive Umfunktionalisierung der terminalen Amidgruppe offenkettiger Polyamide via 2-Oxazolin-5-one als ZwischenstufenZum Teil aus der Diplomarbeit von D.O., Universität Zürich 1980.. Vorläufige MitteilungEine vollständige Mitteilung soll in dieser Zeitschrift erscheinen. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 482-487 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Selective Modification of the Terminal Amide Group of Linear Polyamides via 2-Oxazolin-5-ones as IntermediatesTreatment of aqueous or alcoholic solutions of diamides of type 2 with HCl leads to the formation of amide-acids and amide-esters of type 3 (Scheme 1 and Table). It has been shown, that 2-oxazolin-5-ones of type 4 are intermediates of this selective transformation of the disubstituted terminal amide group. The selectivity of the transformation is demonstrated by the reaction sequence shown in Scheme 3. No selectivity has been observed in the acid-catalyzed hydrolysis of triamide 9 with a monosubstituted terminal amide group (Scheme 4). Hydrolysis of the optically active dipeptide derivatives (+)-(L)-13 and (+)-(L)-15 with HBr in nitromethane at 60-80° yields the pure enantiomer (+)-(L)-14 and (+)-(L)-16, respectively (Scheme 5), i.e., no racemization takes place under the reaction conditions.These results show the usefulness of the dimethylamide group as a protecting group for carboxylic acids for example in the peptide synthesis.
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    Dediazoniations of Arenediazonium Ions in Homogeneous Solution. Part XIV. 15N-CIDNP. Investigation of the reactions of diazonium ions in weakly alkaline aqueous solutionsPresented at the 5th IUPAC Conference on Physical Organic Chemistry, Santa Cruz (Cal.), August 1980. For part XIII: see [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 488-503 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 15N-CIDNP. spectra recorded during the reaction of diazonium cations with OH- in weakly alkaline aqueous solutions show that the dediazoniation is at least partially homolytic. The polarizations observed for the diazonium and trans-diazotate ions can be explained by reaction proceeding via a cage involving diazenyl and diazotate radicals using Kaptein's rules and simple intensity considerations.
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    Dediazoniation of Arenediazonium Ions in Homogeneous Solutions. Part XVII. Kinetics and mechanisms of dediazoniation of p-chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions in the presence of oxygenFor part XVI, s. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 529-546 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of dediazoniation of p-chlorobenzenediazonium tetrafluoroborate have been studied in buffer solutions in the pH-range 9.0-10.0, ionic strength I = 0.10, at 20.0° in glass and polytetrafluoroethylene vessels. The presence of oxygen (〈5 ppb of O2, 60 to 100 ppb of O2, air, 〉 99% of O2) has a decisive influence on the rate and kinetic order of the dediazoniation. Iodoacetic acid inhibits the reaction, whereas p-chlorophenol has a catalytic effect, and in air and 〉99% of O2 it acts as an autocatalyst. The reaction is subject to general-base catalysis by water, hydroxyl ions, hydrogen carbonate and carbonate ions. The kinetic results are interpreted in conjunction with data concerning the reaction products [2] and a 15N-CIDNP. investigation of a related system [3]. Specific radical chain mechanisms are consistent with the results.
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    Preferential Solvation of the Sodium Cation in Binary Mixtures of Tetrahydrofuran with Polyamines, in Relation with the Chelate Effect (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 556-567 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of determining the chelate effect brushes against methodological snags: the choice of concentration units, and of the appropriate standard states. We avoid these pitfalls by defining the chelate effect from measurements on bidentate ligands alone, without recourse to comparison with the corresponding unidentate ligands. Quantitation of the parameters extracted from the data is effected by three independent and mutually consistent procedures. Solvation of the Na+-cation by the polyamines follows the sequence: cadaverin 〈 1, 3-diaminopropane ≪ ethylene diamine ≪ diethylenetriamine. Entry of the first and of the second diamine molecule into the sodium coordination shell are independent and equiprobable steps: K1 = K3 and K2 = K4, within the accuracy of the measurements. For ethylene diamine, the values of K1 and K3 are in the range 1.0-1.5 and those for K2 and K4 are in the range 83-102: attachment of the second N-atom is considerably easier, by two orders of magnitude (chelate effect). The chelate effect is strongly reduced in cadaverin, with a longer hydrocarbon chain connecting the two amine functions.
    Additional Material: 4 Ill.
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    Propellanes. LXII. The endo- and exo-adducts of 11-cyano-1,6-methano[10] annulene with 4-methyl-1,2,4-triazoline-3,5-dionePart LXI: see [1].Dedicated to the memory of Professor Frantisek Šorm (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 579-581 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds have been isolated and their structures determined by X-ray crystallography. Their relative stability is discussed in terms of theory and experiment. The endo-adduct is the thermodynamically more stable one.
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    The Synthesis of Polyfunctional Aromatic Ring Systems. Structural Analogues of Phloroglucides, Aranciamycin, Cryptosporin and Terramycin (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 599-609 
    Details
    ISSN: 0018-019X
    Keywords: Tetracycline-like compounds ; Benzophenone and diphenylmethane derivatives ; Phloroglucide analogues ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the title compounds is described. Some of the compounds prepared were found to be active against a number of pathogenic microorganisms in vitro.
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    Über den Anteil sigmatroper 1, 5-Wanderung von Kohlenwasserstoffgruppen bei der thermolytischen Skelettisomerisierung 5,5-disubstituierter 1, 3-CyclohexadieneVorläufige Mitteilung: [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 801-812 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Extent of Sigmatropic 1, 5-Migration of Hydrocarbon Groups in the Thermolytic Skeletal Rearrangement of 5,5-Disubstituted 1,3-CyclohexadienesThe uncatalyzed skeletal isomerization of 5, 5-disubstituted 1, 3-cyclohexadienes was investigated with the aim to establish the extent to which sigmatropic 1,5-shifts of hydrocarbon groups are participating in these reactions.Gas phase pyrolysis of 5,5-diethyl-1,3-cyclohexadiene (7) at 460° followed by chloranil aromatization yields only 4% of 1,3-diethylbenzene resulting from 7 through a 1, 5-ethyl migration in the primary reaction step. 2, 3-Dimethylethylbenzene (56%) and 1, 4-diethylbenzene (4%) are obtained as other C10-compounds. This shows that isomerization proceeds mainly through a sequence of electrocyclic and 1, 7-shift reactions. Ethylbenzene (24%) and other aromatic C8- and C9-hydrocarbons are formed to a considerable extent, indicating that C, C-bond cleavage is a major competing process and that the 1, 3-diethylbenzene found is the result of a radical recombination reaction and not of a concerted sigmatropic shift of the ethyl group.5-Methyl-5-phenyl-1, 3-cyclohexadiene (12) yields 3-methylbiphenyl (14) and biphenyl upon thermolysis and aromatization. Through 13C-substitution of the methyl group in 12 it is shown that in solution at 300° skeletal isomerization proceeds through electrocyclic and 1, 7-H-shift reactions exclusively. In the gas phase at 500° 4% of the isomerization product is formed by a 1, 5-shift of a substitutent, presumably of the methyl group, through a dissociative mechanism.Thermolysis of 5, 5-diphenyl-1, 3-cyclohexadiene (22) at 560° in the gas phase leads to 1, 1-diphenyl-1, 3, 5-hexatriene (23) and 1-vinyl-4-phenyl-1, 2-dihydronaphthalene (24) through electrocyclic reaction steps. In addition a small amount of m-terphenyl is obtained at high conversion of 22. This indicates that sigmatropic 1,5-phenyl migration can participate in product formation only at high temperature and in the absence of other irreversible pathways to stable products.
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    Studies of molecular ions. IX. Detection of low-lying ‘non-Koopmans’ states in polyacetylene molecular cationsDedicated to Professor Edgar Heilbronner, on the occasion of his 60th birthday, with respect and gratitudeFor part VIII, see [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 823-834 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Comparison of the photoelectron spectra of the title compounds with the electronic absorption spectra of the corresponding radical cations led to the detection of low lying ‘Non-Koopmans’-states in the ionic species.
    Additional Material: 8 Ill.
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    Loss of H2O from M + t-Butyl Complex Ions of Benzyl Alcohol in Isobutane Chemical Ionization Mass SpectrometryPresented, in part at the American Society for Mass Spectrometry, 28th Annual Conference on Mass Spectrometry and Allied Topics, New York, N.Y. (1980). (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 835-843 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In isobutane chemical ionization mass spectrometry benzyl alcohol exhibits ions at m/z 147 (‘M + 39’) that arise by a loss of H2O from [M + C4H9]+, i.e. ‘M + 57’ complex ions. Electrophilic aromatic substitution of a proton at an ortho-position of neutral C6H5CH2OH with [t-C4H9]+ and, alternatively, nucleophilic substitution of H2O at the benzylic carbon in \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm C_6 H_5 CH_2}\mathop {\rm O}\limits^+ {\rm H}_2 $\end{document} with CH2=C (CH3)2 are discussed as possible pathways. Evidence in favor of the latter is derived from the analysis of C6D5CH2OH and C6H5CD2OH for the origin of the H-atoms lost in H2O. The inferred ion structure of m/z 147 is verified by mass-analyzed ion kinetic energy (MIKE.) measurements of its collision-activated (CA.) decomposition. MIKE./CA. spectra of mass-selected m/z 147 ions, once generated by (CI(i-C4H10) from benzyl alcohol and, once, from 2-methyl-4-phenyl-2-butanol match closely and, thus, reflect identical ion structures. With reference to the simple genesis of this ion from the latter precursor, the structure in question can be concluded to be \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm C_6 H_5 CH_2 CH_2}\mathop {\rm C}\limits^+ ({\rm CH}_3)_2 $\end{document} .
    Additional Material: 5 Ill.
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    1-Aryl- und 1-Alkyl-2-phthalimido-diazen-1-oxide, diacylierte Vertreter von trisubstituierten Triazen-1-oxiden: Bildung, Eigenschaften, Stereoisomerisierung und FragmentierungTeilweise vorgetragen am Second IUPAC Symposium on Organic Synthesis, Jerusalem and Haifa, September 1978. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 864-889 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Aryl- and 1-Alkyl-2-phathalimido-diazene-1-oxides, Diacylated Examples of Trisubstituted Triazene-1-oxides: Formation, Properties, Stereoisomerization and Fragmentation1)Oxidatively generated phthalimido-nitrene (1) reacts with nitrosobenzene (8a), p-nitrosotoluene (8b), o-nitrosotoluene (8c), p-dimethylamino-nitrosobenzene (8d), p-methoxycarbonyl-nitrosobenzene (8e), 1, 1-dimethyl-1-nitrosoethane (8f) and nitrosocyclohexane (8g) to give the respective 1-substituted (Z)-2-phthalimidodiazene-1-oxides 14a-g.The constitution of 2-imidodiazene-1-oxides 14 is deduced from their spectroscopic properties. The UV. spectra of 14a-e are similar with those of the corresponding nitrobenzenes 18, thus supporting the concept of comparibility of the phthalimido-N group with an O-atom and indicating that the phthalimido group is not in conjugation with the diazene-oxide function.This is in contrast to the situation in the non-acylated trisubstituted triazene-1-oxides 12, where conjugation is extended over the chain of all three N-atoms as exhibited by the UV. spectra of (Z)-1, 3, 3-triphenyl-, (Z)-3, 3-dimethyl-1-phenyl-, (Z-3-methyl-1, 3-diphenyl-, (Z)-1-(1, 1-dimethylethyl)-3, 3-diphenyl-, and (Z)-1-(1, 1-dimethylethyl)-3, 3-dimethyltriazene-1-oxide (12a-e). These triazene-1-oxides are formed by the reaction of 1, 1-disubstituted hydrazines 11 with three mol-equiv. of nitroso compounds 8 or from equimolar amounts of 11 and 8 in the presence of mercury oxide. Over 90% of 1, 2-diphenyldiazeneoxide (19, R = C6H5) are isolated by the reaction 11 + 3 8a. Possible mechanisms of the reaction of 11 with 8, and of the formation of 12 via triazanols D and of 19 (R = C6H5) via N-Phenylhydroxylamine (20, R = C6H5) are given in Scheme 6 (in the latter case with experimental evidence). An independent synthesis of 12c confirms the constitutional assignment for 12.
    Additional Material: 5 Tab.
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    Zur Konfiguration des Vitamin-D3-Metaboliten 25, 26-Dihydroxycholecalciferol: Synthese von (25S,26)- und (25R,26)-Dihydroxycholecalciferol (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 915-938 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Configuration of the Vitamin-D3-Metabolite 25,26-Dihydroxycholecalciferol: Synthesis of (25S,26)- and (25R,26)-DihydroxycholecalciferolFor selective synthesis of the title compounds, (25S)-1b and (25R)-1b (Scheme 1), the protected cholesterol precursors (25S)-6 and (25R)-6 were prepared from stigmasterol-derived steroid-units 4a-d and C5-side chain building blocks 5a-d by Grignard- or Wittig-coupling (Scheme 2), the configuration at C(25) of the target compounds being already present in the C5-units. Conversion of the cholesterol intermediates to the corresponding vitamin-D3 derivatives was carried out via the 7,8-didehydrocholesterol compounds (25S)-2b and (25R)-2b (Scheme 1), using the established photochemical-thermal transformation of the 5,7-diene system to the seco-triene system of cholecalciferol. The configuration at C(25) of the cholesterol precursors as assigned on basis of the known configuration of the C5-units used, was found to be in agreement with the result of a single crystal X-ray analysis on compound 11. The configuration at C(25) remained untouched on conversion of the cholesterol ring system to the seco-triene system of vitamin D3 as evident from comparison of the lanthanide-induced CD. Cotton effects observed for (25S)-3b and (25S)1b. 25,26-Dihydroxycholecalciferol observed as a natural vitamin-D3 metabolite has (25S)-configuration.
    Additional Material: 2 Ill.
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    Nitrosoalkenes: Synthesis and Reactivity (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1208-1218 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some α- and β-halonitrosoalkenes 1 have been synthesized and characterized. The halogen atoms of the oxime precursors 2 can be substituted by alkoxy groups. Two kinds of cycloaddition reaction of 1 have been observed: (i) reaction of the NO group with dienes gives 3, 6-dihydrooxazine derivatives 6 which isomerise to epoxyepimines 7 in most cases of β-substituted nitrosoalkenes; (ii) if 4, 5-dihydrooxazines 22 are obtained, the cycloaddition of the nitrosoalkenes as 4π-component is presumed.
    Additional Material: 4 Tab.
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    Masthead (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640501
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    Novel Approach to the Synthesis of 6-Substituted 5,6-Dihydro-2(2H)-pyranonesDedicated to Professor George Büchi on the occassion of his 60th birthday (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1247-1256 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Easily accessible dihydropyrans 9, 10, 12 and 19 are precursors for the synthesis of 6-substituted 5,6-dihydro-2 (2H)-pyranones and 6-substituted tetrahydro-2-pyranones. Syntheses of massoia lactone (3), argentilactone (5), tuberolactone (4) and jasmine lactone (2) from acrolein (6), acrolein dimer (7) or glutaraldehyde (16) are described.
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    Photochemische Reaktionen. 121. Mitteilung. Zur Photochemie von ε,ζ-Methano-α,γ-dienonen und 7,8-Methano-1,3,5-trienenHerrn Prof. George H. Büchi zum 60. Geburtstag mit den besten Wünschen gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1235-1246 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemistry of ε,ζ-Methano-α,γ-dienones and 7,8-Methano-1,3,5-trienesIrradiation of the δ-cyclopropyl-dienone (E)-6 (λ ≥ 347 nm) gives (Z)-6, 10 (1,5-sigmatropic H-shift), (E/Z)-9 (electrocyclic process involving C(ε), C(ζ)-cleavage) and 11 (ring opening).The corresponding 6-cyclopropyl-triene (E)-7 gives on singlet excitation (δ 〉 280 nm) 14 (1,5-sigmatropic H-shift) and, to a smaller extent, the bicyclo [3.2.0] heptenyl-dienes (E/Z)-13. However, on triplet excitation (λ ≥ 347 nm, benzophenone) (E)-7 gives (E/Z)-13 as the main products. On both 1π,π*- and 3π,π*-excitation, (Z)-7 and 15 are formed in small amounts.
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    A 13C-NMR. Study of naphthalene chromium complexesNaphthalene Complexes, Part 2. Part 1: [1].. Correlation with reactivity: Nucleophilic aromatic substitution reactions (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1288-1297 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C-NMR. spectra of the series of complexes η6-naphthalene · CrL3 (L—CO (1), PF3 (2), PF2OMe (6), P(OMe)3 (3), C10H8 (= 3 L) (4) and PMe3 (5)) are reported. Definite assignments of the 13C-NMR. resonances were made through the synthesis of [2, 3, 6, 7-2H4]-naphthalene complexes. The coordinated ring 13C-resonance are found to undergo a smooth transition to higher field with increasing donor character of the coligands L. A correlation of the coordination shifts with the reactivity of the coordinated naphthalene is proposed. In complexes containing strong acceptor ligands the naphthalene is activated to attack by nucleophiles. Sequential treatment of complexes 1-4, 6 and [C10H8FeC5H5]+[PF6]- (7) with stabilized carbanions and I2 or Ce(IV)-salt yields α-substituted naphthalenes in the case of 1, 2, 6 and 7 but not in the case of 3 and 4. Treatment of 3 with an excess of HBF4 results not in the expected metal protonation but in a novel ligand transformation to yield 6.
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    Chemical Selectivities Disguised by Mass Diffusion. VII. A simple model of pH-dependence of product distribution in mixing-disguised azo coupling reactionsPart VI and 7th Communication cf. [1].Results taken from the Ph. D. thesis of H. Belevi [2].. 8th Communication on the selectivity of chemical processesDedicated to the memory of Prof. Norbert Ibl (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1599-1617 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present work a mixing-reaction model is developed to describe the influence of the space- and time-dependent concentration of the leaving group on the pre-equilibria of the reactants and thus on the product distribution of mixing-disguised reactions. The modelling is carried out using a typical example of such reactions, namely azo coupling, where the leaving group is a proton. For this reaction, the existence of characteristic sets of parameters is established, for which the product distribution does not depend on the initial pH-value. These sets of parameters define the isoselectivity points.
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    Chemical Selectivities Disguised by Mass Diffusion. VIII. Influence of pH-gradients on the product distribution in mixing-disguised azo coupling reactionsPart VII and 8th Communication cf. [1].Results taken from the Ph. D. thesis of H. Belevi [2].. 9th Communication on the selectivity of chemical processesDedicated to the memory of Prof. Norbert Ibl (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1618-1629 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In mixing-disguised azo coupling reactions the protons which are released during the electrophilic substitution steps cause a pH-gradient in the reaction zone. Since, owing to the acid-base pre-equilibria, these pH-gradients also determine the local concentrations of the reactants in the reaction zone, they also have an influence on the measured product distribution of such fast reactions. In the present work, the product distribution of the azo coupling of 1-naphthol with 4-sulfophenyldiazonium ion was experimentally measured and the results were compared with the distributions predicted from our mixing-reaction model developed previously [1]. Furthermore, some experimental evidence for the existence of isoselectivity points are presented, at which a change of the initial pH-value has no influence on the product distribution.
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    Röntgenstrukturanalysen von Chiralen Ionophoren: NH4NCS-Komplex von 9,9′-Spirobifluoren-22-Krone-5 (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1653-1662 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: X-ray Structure Analyses of Chiral Ionophores: The NH4NCS Complex of 9,9′-Spirobifluorene-22-crown-5In the crystalline NH4NCS complex of 9,9′-spirobifluorene-22-crown-5 (1) the NH4+ ion sits in the centre of the polyether ring, with distances of 2.92-3.15 Å to the five O-atoms and shows at least twofold orientational disorder. In one orientation, three H-atoms point toward O-atoms and the fourth to the N-atom of the anion situated 2.78 Å above the polyether ring. In another, only two H-bonds are formed. The mean planes of the two fluorene parts of the molecule are perpendicular to each other.Crystals of 2,2′-bis (hydroxymethyl)-9,9′-spirobifluorene (2), an intermediate for the synthesis of 1, contain occluded benzene, which cannot be removed under vacuum. X-ray analysis shows that the benzene molecule does not interact with the spirobifluorene in a specific way but merely occupies cages in the crystal packing.
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    Structure Determination of Brominated Morphinan-6-ones by 13C-NMR. Spectroscopy: A novel closure of the oxygen bridge using 4-acetoxymorphinan-6-onesDedicated to Professor George H. Büchi on the occasion of his 60th birthday (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1672-1681 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bromination of (-)-4-hydroxy-N-methylmorphinan-6-one (3), prepared from natural morphine, with 1 mol of bromine in acetic acid, afforded the 1-bromo ketone 5. The structure of 5 was assigned by 13C-NMR.spectroscopy, and confirmed by X-ray diffraction analysis of its hydrobromide salt. It is suggested that monobromination of synthetic (±)-2,4-dihydroxy-N-formylmorphinan-6-one (7) takes in principle a similar course, although the 13C-NMR.spectrum of the primary reaction product 9 could not be measured because of insolubility in commonly used solvents. Monobromination of (-)-4-acetoxy-N-formylmorphinan-6-one (12) of the natural series, and of (±)-2,4-diacetoxy-N-formylmorphinan-6-one (8) of the synthetic series, followed by treatment of the monobrominated ketones with potassium carbonate in methanol resulted in closure of the O-bridge, and afforded after acid hydrolysis, the corresponding 4,5-epoxy-morphinan-6-ones (-)-16 and (±)-17 respectively. This variation of the ring closure reaction represents a novel and convenient method to convert 4-hydroxymorphinan-6-ones into their corresponding 4,5-epoxymorphinan-6-ones, without involving aromatic bromination and with only 1 mol of bromine.
    Additional Material: 1 Ill.
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    Nucleotide. XIVTeil XIII: [1].. Substituierte β-Phenyläthyl-Gruppen. Neue Schutzgruppen für Oligonucleotid-Synthesen nach dem Phosphorsäuretriester-VerfahrenHerrn Prof. Dr. Conrad Hans Eugster in Verbundenheit zum 60. Geburtstag gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1688-1703 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: XIV. Substituted β-Phenyl-ethyl Groups. New Blocking Groups for Oligonucleotide Syntheses by the Phosphotriester ApproachVarious o- and p-substituted β-phenylethanols (2-10) have been synthesized and investigated as blocking groups in the phosphotriester approach. A large number of 5′-O-tritylated thymidine-3′-phosphotriesters (13-36) with two different phosphate protecting groups have been prepared, characterized, and studied according to their chemical stability and usefullness for oligonucleotide syntheses. The combination of a 5′-O-monomethoxytrityl- and a 3′-(2,5-dichlorophenyl, p-nitrophenylethyl)-phosphate function as in 18 turned out to possess optimal properties as a monomeric nucleotide building block due to the fact that these blocking groups can be quantitatively and selectively be removed without harming each other by trifluoroacetic acid in chloroform to 41, by oximate to 42, and by DBU to 43. The base-catalyzed removal of the monosubstituted phenylethyl groups by DBU or DBN respectively as well as the disubstituted phenylethyl groups by triethylamine in aprotic solvents is a β-elimination process leading to phosphodiesters without attack on the P-center.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640547
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    Substituted 2-Phenylnaphthalenes, a New Class of Nematic Liquid Crystals. Preliminary communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1847-1848 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eleven representatives of 6-n-alkoxy- and 6-n-alkanoyloxy-2-(4′-cyanophenyl)-naphthalenes, a new class of nematogens, are described.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640617
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  • 197
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    Kettenverlängerung funktionalisierter Alkanone durch Umlagerung (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1854-1864 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chain Expansion of Functionalized Alkanones by Rearrangement ReactionsIn analogy to the transamidation reactions which were published earlier a method is described to prolong aliphatic C-chains by two or four C-atoms. 1,3-Diketones or 2-nitro alkanones which are monosubstituted at C(2) are condensed with e.g. methyl vinyl ketone. The reaction product is transformed to its chain-prolonged isomer in the presence of strong base via a 4- or 6-membered intermediate. The most effective reagent for the Michael reaction is methyl 3-oxo-4-pentenoate (20). In this case it was possible to convert 3-nitro-2-butanone (21) to methyl 2-acetyl-6-nitro-3-oxoheptanoate (26) in 82% yield.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640619
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  • 198
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    Stereochemistry of the Platinum Catalyzed Hydroformylation of Olefins (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1865-1869 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The deuterioformylation of (Z)- or (E)-2-butene catalyzed by [DIOP]Pt(SnCl3)-ClDIOP=2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane. gives predominantly erythro- or threo-1,3-[2H]2-2-methylbutanal respectively. Hence, hydroformylation by this catalytic system must take place with cis-stereochemistry.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640620
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  • 199
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    Eine ergiebige Herstellung von 1α,3β-Dihydroxy-Δ5-steroiden durch Reduktion von 1α,2α-Epoxy-4,6-dien-3-onen mit Lithium in AmmoniakHerrn Prof. Dr. G. Büchi zum 60. Geburtstag gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1870-1892 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Efficient Procedure for Preparing 1α,3β-Dihydroxy-Δ5-steroids by Reduction of 1α,2α-Epoxy-4,6-dien-3-ones with Lithium in AmmoniaA number of 1α,3β-dihydroxy-Δ5-steroids of the cholestane, (20S)-20-methyl-pregnane (23,24-dinorcholane), pregnane and androstane series were synthesized from common steroidal precursors. A process originally reported by Barton et al., based on 1,4,6-trien-3-ones as intermediates, was used for the introduction of the 1α-hydroxyl function. The last step of this process, consisting of lithium/ammonia reduction of 1α,2α-epoxy-4,6-dien-3-ones, was found to be crucial and therefore subjected to particular study. A reproducible procedure permitting high-yield conversion was developed. It consists of first reducing the epoxydienone with an approximately stoichiometric amount of lithium in ammonia to give, after protonation with ammonium chloride, a 1α-hydroxy-5-en-3-one. This intermediate is then further reduced by repeated alternating treatment with ammonium chloride and an equivalent amount of lithium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640621
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    Zur Chemie der Spiro-β-lactame aus der [2+2]-Cycloaddition von Ketenen an IminolactoneVorgetragen an der Herbstversammlung der Schweizerischen Chemischen Gesellschaft, 8.10.1977, Bern. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1930-1936 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of Spiro-β-lactamsReactions of the easily accessible spiro-β-lactams 1 are described. These comprise hydrogenation, hydrolyses and alcoholyses, reaction with hydrazine, and lead to new heterocyclic compounds. Some further transformations of the products are shown.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19810640625
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