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  • 1
    Electronic Resource
    Electronic Resource
    Complexes with platinum-hydrogen-silver bonds (1993)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 115 (1993), S. 169-175 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00054a023
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  • 2
    Electronic Resource
    Electronic Resource
    Reaktionen von 3-Dimethylamino-2,2-dimethyl-2H-azirin mit. NH-aciden Heterocyclen; Synthese von 4H-imidazolen (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 768-778 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 3-Dimethylamino-2,2-dimethyl-2H-azirine with NH-Acidic Heterocycles; Synthesis of 4H-ImidazolesIn this paper, reactions of 3-dimethylamino-2,2-dimethyl-2H-azirine (1) with heterocyclic compounds containing the structure unit CO—NH—CO—NH are described. 5,5-Diethylbarbituric acid (5) reacts with 1 in refluxing 2-propanol to give the 4H-imidazole derivative 6 (Scheme 2) in 80% yield. The structure of 6 has been established by X-ray crystallography. Under similar conditions 1 and isopropyl uracil-6-carboxylate (7) yield the 4H-imidazole 8 (Scheme 3), the structure of which is deduced from spectral data and the degradation reactions shown in Scheme 3. Hydrolysis of 8 with 3N HCl at room temperature leads to the α-ketoester derivative 9, which in refluxing methanol gives dimethyl oxalate and 5-dimethyl-amino-2,4,4-trimethyl-4H-imidazole (10). On hydrolysis the latter is converted to the known 2,4,4-trimethyl-2-imidazolin-5-one (11) [6]. Quinazolin-2,4 (1H, 3H)-dione (12) and imidazolidinetrione (parabanic acid, 14) undergo with 1 a similar reaction to give the 4H-imidazoles 13 and 15, respectively (Schemes 4 and 5).In Scheme 6 two possible mechanisms for the formation of 4H-imidazoles from 1 and heterocycles of type 16 are formulated. The zwitterionic intermediate f corresponds to b in Scheme 1. Instead of dehydration as in the case of the reaction of 1 with phthalohydrazide [3], or ring expansion as with saccharin and cyclic imides [1] [2], f, undergoes ring opening (way A or B). Decarboxylation then leads to the 4H-imidazoles 17.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620314
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  • 3
    Electronic Resource
    Electronic Resource
    Transition metal complexes with bidentate ligands spanning trans-positions part XVPart XIV: See [1]. X-ray structural and 31P-NMR solution studies of some three-coordinate silver complexes of 2,11-bis[di(tert-butyl)phosphinomethyl]benzo[c]phenathrene and related ligands (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1603-1611 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of three-coordinate bis(dialkylphosphinomethyl)benzo[c]phenanthrene Ag(I) complexes, alkyl= t-Bu, (1b), and cyclohexyl, (1c), anion = BF4, CIO4, CIO4, NO3, Cl, Br, I, have been prepared and thier 31P-NMR characteristics recorded. The solid state structures of [Ag(1b)Br], [Ag(1b)Cl] and [Ag(1b)CIO4] have been determined by X-ray diffraction. The Ag atom in these complexes shows distorted trigonal geometry. Selected bond lengths and angles are as follows: Ag-P = 2.463(4) Å and 2.433(5) Å, P-Ag-P=141.6(2)° in the bromo complex, Ag-P = 2.457(2) Å and 2.427(2) Å, P-Ag-P = 142.6(1)° ion the chloro complex, and Ag-P = 2.394(2) and 2.393 (2) Å, P-AG-P = 161.5(1)° in the perchlorato complex.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670628
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  • 4
    Electronic Resource
    Electronic Resource
    Transition-metal complexes with bidentate ligands spanning trans-position. Part XVIPart XV:[1]. X-ray structural and 31P-NMR solution studies of 2,11-Bis(diethylphosphinomethyl)benzo[c]phenanthrenesilver(I) perchlorate (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 703-711 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of complexes {AgX(1c)} (X = Cl, Br, I, NO3 and ClO4; 1c = 2,11-bis(diethylphosphinomethyl)benzo[c]phenanthrene) is reported. The 31P-NMR spectra of the above complexes were recorded and the 1J(107Ag, 31P) values are compared with the corresponding data for related complexes. The X-ray crystal structure of [Ag(1c)](ClO4) was determined. There are two crystallographically independent molecules in the unit cell each containing two-coordinate silver, the O-atoms of the perchlorate anions being outside bonding range from the central atom. The two molecules, however, show different bonding parameters: Thus for ‘molecule 1’ P(1)—Ag(1)—P(2) = 167.6(1)°, Ag(1)—P(1) = 2.389(3) and Ag(1)—P(2) = 2.393(3) Å, while for ‘molecule 2’ P(3)—Ag(2)—P(4) = 164.8(1)°, Ag(2)—P(3) = 2.377(3), and Ag(2)—P(4) = 2.378(3) Å. These differences are probably due to packing forces in the crystal lattice.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710404
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  • 5
    Electronic Resource
    Electronic Resource
    The Coordination Chemistry of 1,2-Bis[(diphenylphosphino)methyl]benzene with Nickel(II), Palladium(II), Platinum(II), and Platinum(0) and the X-Ray Crystals Structure of [Pt{1,2-bis[(diphenylphospino)methyl]benzene}(C2H4)] (1990)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 2263-2274 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of complexes [MX2(1)] (M = Ni, Pd, and Pi; X - Cl, Br, and I; 1 = 1,2-bis[(diphenylphosphino)methyl]benzene). [Pt(OSO2CH3)Et(1)], [Pt(alkene)(1)] (alkene - C2H2, and CH2 = CHCN), and [(1)Pt-(μ-H)2PtH(1)][BPh4] is reported. Their 1H- and 31P-NMR spectra were recorded and used lor structural assignments. The X-ray crystal structure of [Pt(C2H4)(1)] was determined. It is shown that the P—Pt—P bond angle in this complex differs significantly from those found in related compounds with monodentate phosphines, and that this difference is likely to be due to intramolecular contacts.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19900730823
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  • 6
    Electronic Resource
    Electronic Resource
    Struktur des Hydrazinolyseproduktes von N-(3-Oxo-1-isoindolinyliden)-alanin-äthylester (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 1797-1804 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrazinolysis of N-(3-Oxo-1-isoindolinyliden)alanin Ethyl Ester, Structure of the ProductTreatment of N-(3-oxo-1-isoindolinyliden)alanin ethyl ester (6) with hydrazine hydrate leads to 4-methyl-2,3,4,6-tetrahydro[1,2,4]triazino[3,4-a]isoindole-3, 6-dione (8, Scheme 3) and not to the previously postulated 6-hydroxy-2-methyl-2,3-dihydro-imidazo [2,1-a]phthalazin-3-one (7, cf. [2]). The structure of 8 has been established by an independent synthesis as well as by the X-ray analysis of the reaction product 11 from 8 and 3-dimethylamino-2,2-dimethyl-2 H-azirine (1, Scheme 4). A reaction mechanism for the formation of 8 from 6 is suggested in Scheme 5.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630707
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  • 7
    Electronic Resource
    Electronic Resource
    Reaktion von 3-Dimethylamino-2,2-dimethyl-2H-azirin mit Barbitursäure (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 49-63 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of 3-Dimethylamino-2,2-dimethyl-2H-azirine with Barbituric AcidThe reaction of 3-dimethylamino-2,2-dimethyl-2H-azirine (1) with barbituric acid (4) in dimethyl formamide at room temperature yields a mixture of several compounds. The two main products 5 and 6 have been isolated in 40 and 10% yield, respectively, and their structures established by X-ray analysis. In Schemes 4-6 reaction mechanisms for the formation of 5 and 6 are postulated, the first step beeing either a C- or an N-alkylation of barbituric acid.Reduction of 5 and 6 with NaBH4 in ethanol at room temperature yields 6,6-dimethyl-1,5,6,7-tetrahydro-pyrrolo[2,3-d]pyrimidin-2,4(3H)-dione (7) and 3,3-dimethyl-2,3-dihydro-imidazo[1,2-c]pyrimidin-5,7(1H, 6H)-dione (8) in 38 and 48% yield, respectively. Treatment of 6 with 3N aqueous NaOH at room temperature gives 3,3-dimethyl-imidazo[1,2-c]pyrimidin-2,5,7 (1H, 3H, 6H)-trione (9) in 51% yield (Scheme 3).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640108
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  • 8
    Electronic Resource
    Electronic Resource
    Bortrifluorid-katalysierte Umsetzung von 3-Amino-2H-azirinen mit Amiden: Bildung von 4,4-disubstituierten 4H-ImidazolenHerrn Prof. Dr. Richard Neidlein zum 65. Geburtstag gewidmet (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 899-909 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Boron Trifluoride Catalyzed Reaction of 3-Amino-2H-azirines and Amides: Formation of 4,4-Disubstituted 4H-ImidazolesReaction of trifluoroacetamide and 3-amino-2H-azirines 1 in refluxing MeCN affords 4-amino-2-(trifluoromethyl)-4H-imidazoles 5 in fair yields (Scheme 3). Less acidic amides do not react with 1 under similar conditions. Therefore, a procedure involving BF3-catalysis has been elaborated: the aminoazirine 1 in CH2Cl2 at -78° is treated with BF3 · Et2O and then with a solution of the sodium salt of an amide in THF, prepared by addition of sodium hexamethyldisilazane at -78°. The 4H-imidazoles of type 5 are formed in ca. 50% yield (Scheme 4). Reaction mechanisms for this ring enlargement of 1 are proposed in Schemes 5 and 6.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780413
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  • 9
    Electronic Resource
    Electronic Resource
    Tieftemperaturbestrahlungen von 3-Phenyl-2H-azirinen27. Mitt. über Photoreaktionen; 26. Mitt. [1]. 25. Mitt. [2]. (1973)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 56 (1973), S. 1679-1690 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2, 2, 3-Triphenyl-2H-azirine (4a) in a matrix of 2, 2-dimethylbutane/pentane 8:3 (DMBP) at -185° gave rise on irradiation with light of 250-350 nm to a new UV.-maximum at 350 nm (Fig. 1). We assign the dipole benzonitrildiphenylmethylide (1a) to this new maximum. Irradiation with monochromatic light of 366 nm destroyed this maximum and the initial absorption curve reappeared (Fig. 2). When the azirine 4a was photolysed in DMBP at -185° in the presence of methyl trifluoracetate (TFEM), the maximum at 350 nm was obtained again. This maximum vanished upon increasing the temperature to -160°. Through gas chromatography we were able to show that 5-methoxy-5-trifluormethyl-2, 2, 4-triphenyl-3-oxazoline (6a) was produced. 6a was also obtained upon irradiation of 4a at room temperature in the presence of TFEM (scheme 1 and table 1). Modification of the previously described experiment, in which the maximum at 350 nm was extinguished in the matrix due to irradiation at 366 nm gave, after warm up, almost no dipole adduct 6a (table 1). From these experiments, an extinction coefficient of 17, 000 for the 350 nm maximum of 1a, was calculated. These experiments have shown that irradiation of triphenylazirine 4a leads to the dipole 1a, which can be reversed photochemically - but not tharmally - into azirine 4a. 1a reacts at less than -160° with TFEM to give adduct 6a. The results which were obtained with triphenylazirine 4a could be correspondingly obtained with 2, 3-diphenyl-2H-azirine 4b (Fig. 3, scheme 2 and table 2). The dipole 1b showed two UV.-maxima at 330 nm (ε = 17, 500) and 343 nm (ε = 21, 000). Later experiments established, that the two maxima belonged to a single dipole species.The dipole 1c obtained upon irradiation of 2, 2-dimethyl-3-phenyl-2H-azirine (4c) in DMBP at -190°, appears to absorb in the same region as the azirine 4c. The presence of the dipole 1c was univocally established by low temperature trapping experiments with TFEM. The dipole 1a showed no ESR.-spectrum characteristic for a triplet state. We assume therefore, that 1a is in a singlet state. Photolysis of oxazolinone 7 at -190° in DMBP led to the dipole 1a with loss of CO2. 1a recombines apparently in considerable amount with the CO2 trapped in the matrix to give starting oxazolinone 7 because the 350 nm-maximum of 1a appeared with low extinction. Irradiation with light of 366 nm into this matrix produccd triphenylazirine 4a. Low temperature trapping experiments with TFEM led to small amounts of 5-methoxy-5-trifluormethyl-triphenyl-3-oxazolinc (6a).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19730560525
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  • 10
    Electronic Resource
    Electronic Resource
    Reaktionsprodukte aus 3-Dimethylamino-2, 2-dimethyl-2H-azirin und Phthalohydrazid bzw. Maleohydrazid (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 2116-2129 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction Products from 3-Dimethylamino-2,2-dimethyl-2H-azirine and Phthalohydrazide or Maleohydrazide3-Dimethylamino-2, 2-dimethyl-2H-azirine (1) reacts in dimethylformamide at room temperature with the six-membered cyclic hydrazides 2, 3-dihydrophthalazin-1, 4-dione (2) and 1, 2-dihydropyridazin-3, 6-dione (15) to give the zwitterionic compounds 3 and 16, respectively (Scheme 1 and 7). The mechanism of these reactions is outlined in Scheme 1 for compound 3 (cf. also Scheme 8). The first steps are thought to be similar to the known reactions of 1 with the NH-acidic compounds saccharin and phthalimide (cf. [1]). Instead of ring expansion to the nine-membered heterocycle i (X=CONH, Scheme 8), a proton transfer followed by the loss of water gives 3 (Scheme 1).The structure of the zwitterionic compounds 3 and 16 is deduced from spectral data and the reactions of these compounds (see Schemes 2, 3, 4, 6 and 7). Methylation of 3 yields the iodide 4, which is hydrolysed easily to the 2-imidazolin-5-one derivative 5 (Scheme 2). Hydrolysis of 3 under basic conditions leads to the amide 6, which undergoes cyclization to 7 at 220-230° (Scheme 3). The analogous cyclization has been realized under acidic conditions in the case of 17 (Scheme 7).Catalytic reduction of 3 yields the tertiary amine 14 (Scheme 6), whereas the reduction with sodium borohydride leads to a mixture of 14 and the 2-imidazoline derivative 13. The alcohol 11, corresponding to the amine 14, is obtained by sodium borohydride reduction of the 2-imidazolin-5-one 7 or of the amide 6 (Scheme 3). This remarkably easy reaction of 7 shows the unusual electrophilicity of the lactamcarbonyl group in this compound. The reduction of 6 to 11 is understandable only by neighbouring group participation of N (2′) in the dihydrophthalazine residue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610619
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