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  • 11
    Digitale Medien
    Digitale Medien
    Umsetzung von Di(tert-butyl)- und Diphenyldiazomethan mit 1,3-Thiazol-5(4H)-thionen: Isolierung und Kristallstruktur des primären Cycloadduktes (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 435-444 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaction of Di(tert-butyl)- and Diphenyldiazomethane and 1,3-Thiazole-5(4H)-thiones: Isolation and Crystal Structure of the Primary CycloadductReactions of diazo compounds with C=S bonds proceed via the formation of thiocarbonyl ylides, which, under the reaction conditions, undergo either 1,3-dipolar cycloadditions or electrocyclic ring closer to thiiranes (Scheme 1). With the sterically hindered di(tert-butyl)diazomethane (2c), 1,3-thiazole-5(4H)-thiones 1 react to give spirocyclic 2,5-dihydro-1,3,4-thiadiazoles 3 (Scheme 2). These adducts are stable in solution at -20°, and they could be isolated in crystalline form. The structure of 3c was established by X-ray crystallography. In CDCl3 solution at room temperature, a cycloreversion occurs, and the adducts of type 3 are in an equilibrium with 1 and 2c. In contrast, the reaction of 1 with diphenyldiazomethane (2d) gave spirocyclic thiiranes 4 as the only product in high yield (Scheme 3). The crystal structure of 4b was also determined by X-ray analysis. The desulfurization of compounds 4 to 4,5-dihydro-5-(diphenylmethylidene)-1,3-thiazoles 5 was achieved by treating 4 with triphenylphosphine in boiling THF. The crystal structure of 5f is shown.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19940770204
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  • 12
    Digitale Medien
    Digitale Medien
    Umsetzung von Diazoessigsäure-ethylester mit 1,3-Thiazol-5(4H)-thionen (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 1299-1312 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaction of Ethyl Diazoacetate with 1,3-Thiazole-5(4H)-thionesReaction of ethyl diazoacetate (2a) and 1,3-thiazole-5(4H)-thiones 1a,b in Et2O at room temperature leads to a complex mixture of the products 5-9 (Scheme 2). Without solvent, 1a and 2a react to give 10a in addition to 5a-9a. In Et2O in the presence of aniline, reaction of 1a,b with 2a affords the ethyl 1,3,4-thiadiazole-2-carboxylate 10a and 10b, respectively, as major products. The structures of the unexpected products 6a, 7a, and 10a have been established by X-ray crystallography. Ethyl 4H-1,3-thiazine-carboxylate 8b was transformed into ethyl 7H-thieno[2,3-e][1,3]thiazine-carboxylate 11 (Scheme 3) by treatment with aqueous NaOH or during chromatography. The structure of the latter has also been established by X-ray crystallography. In the presence of thiols and alcohols, the reaction of 1a and 2a yields mainly adducts of type 12 (Scheme 4), compounds 5a,7a, and 9a being by-products (Table 1). Reaction mechanisms for the formation of the isolated products are delineated in Schemes 4-7: the primary cycloadduct 3 of the diazo compound and the C=S bond of 1 undergoes a base-catalyzed ring opening of the 1,3-thiazole-ring to give 10. In the absence of a base, elimination of N2 yields the thiocarbonyl ylide A′, which is trapped by nucleophiles to give 12. Trapping of A′, by H2O yields 1,3-thiazole-5(4H)-one 9 and ethyl mercaptoacetate, which is also a trapping agent for A′, yielding the diester 7. The formation of products 6 and 8 can be explained again via trapping of thiocarbonyl ylide A′, either by thiirane C (Scheme 6) or by 2a (Scheme 7). The latter adduct F yields 8 via a Demjanoff-Tiffeneau-type ring expansion of a 1,3-thiazole to give the 1,3-thiazine.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19940770512
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  • 13
    Digitale Medien
    Digitale Medien
    Carbenoid Reactions of Dimethyl Diazomalonate with Aromatic Thioketones and 1,3-Thiazole-5(4H)-thiones (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1785-1792 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dimethyl diazomalonate (4) and thiobenzophenone (2a) do not react in toluene even after warming to 50°. After addition of catalytic amounts of Rh2(OAc)4, a smooth reaction under N2 evolution afforded a mixture of thiiranedicarboxylate 5 and (diphenylmethylidene)malonate 6 (Scheme 2). A reaction mechanism via an intermediate ‘thiocarbonyl ylide’ 7, formed by the addition of the carbenoid species 8 to the S-atom of 2a, is plausible. Similar reactions were carried out with 9H-xanthene-9-thione (2b), 9H-thioxanthene-9-thione (2c, Scheme 4), and 1,3-thiazole-5(4H)-thione 18 (Scheme 6). In the cases of 2b and 2c, spirocyclic 1,3-dithiolanetetracarboxylates 14a and 14b, respectively, were obtained as the third product. Reaction mechanisms for their formation are proposed in Scheme 5: S-transfer from intermediate thiirane 12 to the carbenoid species yielded thioxomalonate 15 which underwent a 1,3-dipolar cycloaddition with ‘thiocarbonyl ylide’ 16. An alternative is the formation of ‘thiocarbonyl ylide’ 17 via carbene addition to 15, followed by 1,3-dipolar cycloaddition with 2b and 2c, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19960790704
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  • 14
    Digitale Medien
    Digitale Medien
    Reaktion von 2-Diazopropan mit 1,3-Thiazol-5(4H)-thionen (1992)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 75 (1992), S. 1825-1833 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaction of 2-Diazopropane and 1,3-Thiazole-5(4H)-thionesAt 0°, 1,3-thiazoles 1 and 2-diazopropane in pentane or MeOH undergo a smooth 1,3-dipolar cycloaddition to give spirocyclic 2,4-dihydro-1,3,4-thiadiazoles 6 (Scheme 3). Elimination of N2 occurs already at 20°, yielding spirocyclic thüranes 7. At room temperature, the latter decompose slowly to give 4,5-dihydro-5-isopropylidene-1,3-thiazoles 8. The desulfurization 7 → 8 can be accelerated by heating or by addition of trimethyl phosphite. The intermediate of the N2 elimination of 6 is a thiocarbonyl ylide D which can be trapped with the reactive dipolarophiles thiobenzophenone and fumarodinitrile (Scheme 4). In the absence of these trapping reagents, D undergoes ring closure to thüranes 7. The cycloaddition of D and a second molecule of 1, the so-called Schönberg reaction, is not observed.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19920750608
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  • 15
    Digitale Medien
    Digitale Medien
    Umsetzung von 1,3-Thiazol-5(4H)-thionen mit DiazomethanHerrn Professor Rolf Huisgen zum 73. Geburtstag gewidmet (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1715-1728 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaction of 1,3-Thaiazole-5(4H)-thiones and DiazometaneReaction of 4,4-dimethyl-1,3-thiazol-5(4H)-thiones 1 with diazomethane in Et2O at -78° or 0° leads to a mixture of the corresponding 1,4-dithiane 10,1,3-dithiole 11, thiirane 12, 4,5-dihydro-5methylidene-1,3-thiazole 13, and 1,3-thiazol-5(4H)-one 14 (Scheme 3). The structures of 10a, 11a, and 11bhave been established by X-ray crystallography. The formation of the products can be explained via an intermediate thiocaronyl ylide of type E (Scheme 4), generated by the 1.3-dipolar cycloaddition of diazomethane with the exocyclic C=S bond of 1 and elimination of N2. Head-to-head dimerization of E yields 10, 1, 3-dipolar cycloaddition of E and 1 gives the ‘Schönberg product’ 11, and cyclization of E leads to 12, which undergoes a desulfurization to give 13. The thiazolone 141 is formed by hydolysis of E. The similarity of the ratio of the products at -78° and at 0° shows that, in contrast to the reaction of 1 and 2-diazopropane, the elimination of N2 in the primary cycloadduct already occurs at -78°.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19930760428
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  • 16
    Digitale Medien
    Digitale Medien
    Reaktion von Phenyldiazomethan mit 1,3-Thiazol-5(4H)-thionen: Basenkatalysierte Ring-Öffnung des Primäradduktes (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 1076-1086 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaction of Phenyldiazomethane with 1,3-Thiazole-5(4H)-thiones: Base-Catalyzed Ring Opening of the Primary AdductReaction of 1,3-thiazole-5(4H)-thiones 1 and phenyldiazomethane (2a) in toluene at room temperature yields the thiiranes trans- and cis-1,4-dithia-6-azaspiro[2.4]hept-5-enes (trans- and cis-4; Scheme 2). With Ph3P in THF at 70°, these thiiranes are transformed stereospecifically into (E)- and (Z)-5-benzylidene-4,5-dihydro-1,3-thiazoles 5, respectively. In the presence of DBU, 1 and 2a react to give 1,3,4-thiadiazole derivatives 6 or 7 via base-catalyzed ring opening of the primary cycloadduct (Scheme 3). In the case of 2-(alkylthio)-substituted 1,3-thiazole-5(4H)-thiones 1c and 1d, this ring opening proceeds by elimination of the corresponding alkylthiolate, yielding isothiocyanate 7. The structures of (Z)-5c and 6b have been established by X-ray crystallography.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19940770421
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  • 17
    Digitale Medien
    Digitale Medien
    1,3-Dipole mit zentralem S-Atom aus der Umsetzung von Aziden mit Thiocarbonyl-Verbindungen: Eine unerwartete MeS-Wanderung im Abfangprodukt eines ‘Thiocarbonyl-aminids’ mit Dithiobenzoesäure-methylesterTeilweise von G.M. an der Jahresversammlung der Polnischen Chemischen Gesellschaft in Warschau, September 1994, vorgetragen.Herrn Professor Dr. Klaus Hartke in Würdigung seiner Beiträge zur Schwefelorganischen Chemie gewidmet (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 1499-1510 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,3-Dipoles with a Central S-Atom from the Reaction of Azides and Thiocarbonyl Compounds: An Unexpected MeS Migration in the Trapping Product of a ‘Thiocarbonyl-aminide’ with Methyl DithiobenzoateReaction of PhN3 with O-methyl thiobenzoate (11a) and thioacetate (11c) as well as with the dithio esters 11b,d at 80° yields the corresponding imidates and thioimidates 12 (Scheme 3). The formation of 12 is rationalized by a 1,3-dipolar cycloaddition of the azide and the C=S group followed by successive elimination of N2 and S. In the three-component reaction of 11b, PhN3, and the sterically crowded thioketone 1a, 1,2,4-trithiolane 13a and 1,4,2-dithiazolidine 3a are formed in addition to 12b (Scheme 4). The heterocycles 13a and 3a are trapping products of 1a and ‘thiocarbonyl-thiolate’ 5a and ‘thiocarbonyl-aminide’ 2a (Ar=Ph), respectively (Scheme 6). These 1,3-dipoles are formed as reactive intermediates. Surprisingly, in the presence of catalytic amounts of acids, the major product is the (methyldithio)cyclobutyl thioimidate of type 14 (Scheme 5), formed by an acid-catalyzed MeS migration in dithiazolidine 17. A reaction mechanism is proposed in Scheme 7.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19950780609
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  • 18
    Digitale Medien
    Digitale Medien
    Three-Component Reactions with Sterically Crowded 2,2,4,4-Tetramethyl-3-thioxocyclobutanone, Phenyl Azide, and Electron-Deficient C,C-DipolarophilesPresented by G.M. at the ‘17th International Symposium on the Organic Chemistry of Sulfur’, Tsukuba, Japan, July 1996.Dedicated to Professor Vladimir Prelog on the occasion of his 90th birthday (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1305-1314 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In order to trap ‘thiocarbonyl-aminides’ A, formed as intermediates in the reaction of thiocarbonyl compounds with phenyl azide, a mixture of 2,2,4,4-tetramethyl-3-thioxocyclobutanone (1), phenyl azide, and fumarodinitrile (8) was heated to 80° until evolution of N2 ceased. Two interception products of the ‘thiocarbonylaminide’ A (Ar=Ph) were formed: the known 1,4,2-dithiazolidine 3 (cf. Scheme 1) and the new 1,2-thiazolidine 12 (Scheme 2). The structure of the latter was established by X-ray crystallography (Fig.1). The analogous ‘three-component reaction’ with dimethyl fumarate (9) yielded, instead of 8, in addition to the known interception products 3 and 6 (Scheme 1), two unexpected products 15 and 16 (Scheme 3), of which the structures were elucidated by X-ray crystallography (Fig.2). Their formation is rationalized by a primary [2 + 3] cycloaddition of diazo compound 18 with 1 to give 19, followed by a cascade of further reactions (Scheme 4).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19960790507
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  • 19
    Digitale Medien
    Digitale Medien
    Synthese von Trifluoromethyl-substituierten Schwefel-Heterocyclen unter Verwendung von 3,3,3-Trifluorobrenztraubensäure-DerivatenVorgetragen von H. H. am ‘Symposium on Fluoroorganic Chemistry’, Warschau, 17. Mai 1996. (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1537-1548 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis of Trifluoromethyl-Substituted Sulfur Heterocycles Using 3,3,3-Trifluoropyruvic-Acid DerivativesThe reaction of methyl 3,3,3-trifluoropyruvate (1) with 2,5-dihydro-1,3,4-thiadiazoles 4a, b in benzene at 45° yielded the corresponding methyl 5-(trifluoromethyl)-1,3-oxathiolane-5-carboxylates 5a, b (Scheme 1) via a regioselective 1,3-dipolar cycloaddition of an intermediate ‘thiocarbonyl ylide’ of type 3. With methyl pyruvate, 4a reacted similarly to give 6 in good yield. Methyl 2-diazo-3,3,3-trifluoropropanoate (2) and thiobenzophenone (7a) in toluene underwent a reaction at 50°; the only product detected in the reaction mixture was thiirane 8a (Scheme 2). With the less reactive thiocarbonyl compounds 9H-xanthene-9-thione (7b) and 9H-thioxanthene-9-thione (7c) as well as with 1,3-thiazole-5(4H)-thione 12, diazo compound 2 reacted only in the presence of catalytic amounts of Rh2(OAc)4. In the cases of 7a and 7b, thiiranes 8b and 8c, respectively, were the sole products (Scheme 3). The crystal struture of 8c has been established by X-ray crystallography (Fig.). In the reaction with 12, desulfurization of the primarily formed thiirane 14 gave the methyl 3,3,3-trifluoro-2-(4,5-dihydro-1,3-thiazol-5-ylidene)propanoates (E)-and (Z)-15 (Scheme 4). A mechanism of the Rh-catalyzed reaction via a carbene addition to the thiocarbonyl S-atom is proposed in Scheme 5.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19960790604
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  • 20
    Digitale Medien
    Digitale Medien
    Bildung von 1,2,4-Trithiolanen in Dreikomponenten-Gemischen aus Phenyl-azid, aromatischen Thioketonen und 2,2,4,4-Tetramethylcyclobutanthionen: Eine Schwefel-Transfer-Reaktion unter Bildung von ‘Thiocarbonylthiolaten’ ((Alkylidensulfonio)thiolaten) als reaktive ZwischenstufenAnstelle von ‘Thiocarbonyl-thiolat’ werden häufig auch die Bezeichnungen ‘Thiocarbonyl-sulfid’, ‘Thion-S-sulfid’ und ‘Thiosulfin’ verwendet.Teilweise von G.M. anlässlich des ‘Sixteenth International Symposium on the Organic Chemistry of Sulfur’, in Merseburg, Juli 1994, vorgetragen.Herrn Professor Dr. Rolf Huisgen zum 75. Geburtstag Gewidmet (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 1298-1310 
    Details
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Formation of 1,2,4-Trithiolanes in Three-Component Reactions of Phenyl Azide, Aromatic Thiones, and 2,2,4,4-Tetramethylcyclobutanethiones: A Sulfur-Transfer Reaction to ‘Thiocarbonyl-thiolates’ ((Alkylidenesulfonio)-thiolates) as Reactive IntermediatesThe reaction of PhN3 and aromatic thioketones 18 (two-component reaction) at 80° yields only the corresponding imines 22, S, and N2. Under similar conditions, in the presence of sterically crowded 2,2,4,4-tetramethyl-cyclobutanethiones 19 (three-component reaction), 1,2,4-trithiolanes of type 20 are formed in good yields in addition to imines 22 (Scheme 4). In case of 19a and 19c (X = CO, CS), the symmetrical trithiolanes 21a and 21b, respectively, are also isolated. With 4,4-dimethyl-2-phenyl-1,3-thiazole-5(4H)-thione (24) instead of aromatic thioketone 18, imine 25, trithiolane 21a, and 1,4,2-dithiazolidine 26 are formed (Scheme 5). A reaction mechanism for the formation of 1,2,4-trithiolanes 20 and 21, including an S-transfer to generate ‘thiocarbonyl-thiolates’ 2b and/or 2c and 1,3-dipolar cycloaddition with a thioketone, is proposed in Scheme 7.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/hlca.19950780520
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