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  • Organic Chemistry  (54)
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  • 11
    Electronic Resource
    Electronic Resource
    A Ring Enlargement from Seven- to Ten-Membered-Ring sulfonamide derivatives (1996)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 1121-1128 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 3-(dimethylamino)-2,2-dimethyl-2H-azirine (1a) with 4,5-dihydro-7,8-dimethoxy-1,2-benzothiazepin-3-one 1,1-dioxide (4) in dioxane at room temperature gave the correspondingly substituted 4H-1,2,5-benzothiadiazecin-6-one 1,1-dioxide 5a in 64% yield (Scheme 2). The structure of this novel ten-membered ring-enlargement product was established by X-ray crystallography (Fig.). Under more vigorous conditions (refluxing dichloroethane), 5a was formed together with the isomeric 6a, both in low yield. The 3-(dimethylamino)-2H-azirines 1b and 1c reacted sluggishly to give the two isomeric ring-enlargement products of type 5 and 6 in yields of 24-29% and 2-4%, respectively (Table 1). Even less reactive is 2,2-dimethyl-3-(N-methyl-N-phenylamino)-2H-azirine (1d), which reacted with 4 in MeCN only at 65°. Under these conditions, besides numerous decomposition products, only traces of 5d and 6d were formed. No ring enlargement was observed with the sterically crowded 1e, which bears an isopropyl group at C(2).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19960790420
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  • 12
    Electronic Resource
    Electronic Resource
    Ringöffnungen von sterisch gehinderten spirocyclischen 2, 5-Dihydro-1, 3, 4-thiadiazolen mit cycloaliphatischen, sekundären AminenHerrn Professor Waldemar Adam zum 60. Geburtstag gewidmet (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 230-240 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring Opening of Sterically Crowded Spirocyclic 2, 5-Dihydro-l, 3, 4-thiadiazoles by Cycloaliphatic Secondary AminesAt room temperature, the spirocyclic 2, 5-dihydro-l, 3, 4-thiadiazole 3 reacted with cyclic secondary amines 6 via ring opening to give N-alkylidene-hydrazones of type 7 (Scheme 2). A reaction mechanism via a base-catalyzed transformation of the dihydrothiadiazole ring to the corresponding thiolate 19 and the intermediate thioaldehyde 21 is proposed in Scheme 6. An analogous reaction occurred with the mixture of the dispiro compounds 4/5 and morpholine (6a) or azetidine (6d), leading to a mixture of isomeric dihydrazones 8 and 9 (Scheme 3). The structure of the symmetrical isomer 8a was established by X-ray crystallography. In addition to 8a and 9a, the thiirane lOa (Scheme 3) was isolated as a minor product.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800121
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  • 13
    Electronic Resource
    Electronic Resource
    1,3-Dipolare Cycloadditionen eines Carbonyl-ylids mit 1,3-Thiazol-5(4H)-thionen und Thioketonen (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1190-1204 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dipolar Cycloadditions of a Carhonyl-ylide with 1,3-Thiazole-5(4H)-thiones and ThioketonesInp-xylene at 150°, 3-phenyloxirane-2,2-dicarbonitrile (4b) and 2-phenyl-3-thia-1-azaspiro[4.4]non-1-ene-4-thione (1a) gave the three 1:1 adduets trans-3a, cis-3a, and 13ain 61, 21, and 3% yield, respectively (Scheme 3). The stereoisomers trans-3a and cis-3a are the products of a regioselective 1,3-dipolar cycloaddition of carbonylylide 2b, generated thermally by an electrocyclic ring opening of 4b (Scheme 6), and the C=S group of 1a. Surprisingly, 13a proved not to be a regioisomeric cycloadduct of 1a and 2b, but an isomer formed via cleavage of the O—C(3) bond of the oxirane 4b. A reaction mechanism rationalizing the formation of 13a is proposed in Scheme 6. Analogous results were obtained from the reaction of 4b and 4,4-dimethyl-2-phenyl-1,3-thiazole-5 (4H)-thione (1b, Scheme 3). The thermolysis of 4b in p-xylene at 130° in the presence of adamantine-thione (10) led to two isomeric 1:1 adducts 15 and 16 in a ratio of ca. 2:1, however, in low yield (Scheme 4). Most likely the products are again formed viathe two competing reaction mechanisms depicted in Scheme 6. The analogous reactions of 4b with 2,2,4,4-tetramethylcyclobutane-1,3-thione (11) and 9H-xanthene-9-thione (12) yielded a single 1:1 adduct in each case (Schemes). In the former case, spirocyclic 1,3-oxathiolane 17, the product of the 1,3-dipolar cycloaddition with 2a corresponding to 3a, was isolated in only 11 % yield. It is remarkable that no 2:1 adduct was formed even in the presence of an excess of 4b. In contrast, 4b and 12 reacted smoothly to give 18 in 81 % yield; no cycloadduct of the carbonylylide 2a could be detected. The structures of cis-3a, 13a, 15, and 18, as well as the structure of 14, which is a derivative of trans-3a, have been established by X-ray crystallography (Figs. 1-3, Table).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800417
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  • 14
    Electronic Resource
    Electronic Resource
    Reaction of N,N'-dimethyl-2-nitroethene-1, 1-diamine with α,ß-unsaturated acyl isothiocyanates: Preparation of 1,3-thiazin-4-one and 4-nitro-1,2-thiazol-5(2H)-imine derivativesPresented in preliminary form at the ‘XII seminario cientifico’, centro nacional de investigaciones cientificas, habana, cuba, 1995 (M. I. G. T.) and at the ‘tenth international conference on organic synthesis’, Bangalore, India, 1994 (D. M. A.). (1998)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 718-728 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of N,N'-dimethyl-2-nitroethene-1,1-diamine (8) with α,ß-unsaturated acyl isothiocyanates 9 affords 3,3-diamino-2-nitroacrylthioamides 10 (Scheme 2) in moderate-to-good yields. Cyclization of 10 under acidic conditions gives 1,3-thiazin-4-one derivatives of type 11. Oxidative cyclization of 10 with diethyl azodicaboxylate leads to 4-nitro-1,2-thiazol-5(2H)-imine derivatives 12.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19980810321
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  • 15
    Electronic Resource
    Electronic Resource
    Diastereo- and Regioisomeric Bicyclic Thiohydantions from Chiral 1,3-Thiazolidine-2,4-dicarboxylic acids (1998)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 744-753 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bicyclic thiohydantoins were synthesized in a stereoselective manner by reacting (2R)/(2S)-diastereoisomer mixtures of 1,3-thiazolidine-2,4-dicarboxylic acids or their dimethyl diesters with PhNCS. 5,5-Dimethyl-1,3-thiazolidine-2,4-dicarboxylic acid with PhNCS led to a cyclization involving the C=O group at the C(2) center of the thiazolidine ring, while the acid's dimethyl diester gave cyclization involving the C=O group at C(4). In contrast, reactions involving unsubstituted 1,3-thiazolidine-2,4-dicarboxylic acid or its dimethyl diester led to thiohydantoins in which the ring closure had taken place only with the COO group at C(4). Independently of the direction of the ring closure, all reactions produce exclusively products with the (R)-configuration at C(2). The configurational assignments were based on 1H- and 13C-NMR studies, and confirmed by X-ray crystallographic analyses.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19980810324
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  • 16
    Electronic Resource
    Electronic Resource
    [2+3] Cycloadditions of ‘Thiocarbonyl Ylides’ (= (Alkylidenesulfonio)methanides) and diazoalkanes with N,N′-(thiocarbonyl)diimidazole (= 1,1′-(carbonothioyl)bis[1H-imidazole])Part of the planned Ph.D. Thesis of T.G., University of Łódź.Dedicated to Professor Romuald Bartnik (University of Łódź) on the occasion of his 60th birthday (1998)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 66-77 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heating of a mixture of N,N′-(thiocarbonyl)diimidazole (= 1,1′-(carbonothioyl)bis[1H-imidazole]; 1) and 2,5-dihydro-1,3,4-thiadiazole 2a or 2b gave the 1,3-dithiolanes 4a and 4b, respectively, via a regiospecific 1,3-dipolar cycloaddition of the corresponding ‘thiocarbonyl methanides’ 3a,b onto the C=S group of 1 (Schemes 1 and 2). The adamantane derivative 4b was not stable in the presence of 1H-imidazole and during chromatographic workup. The isolated 1,3-dithiole 5 is the product of a base-catalyzed elimination of 1H-imidazole from the initial cycloadduct 4b. The formation of the S,N-acetal 6 can be rationalized by a protonation of the ‘thiocarbonyl ylide’ 3b followed by a nucleophilic addition of 1H-imidazole. With the diazo compounds 8a-e (Scheme 3) 1 underwent a regiospecific 1,3-dipolar cycloaddition to give the corresponding 2,5-dihydro-1,3,4-thiadiazole derivatives 9, which spontaneously eliminated 1H-imidazole to yield (1H-imidazol-1-yl)-1,3,4-thiadiazoles 10. The structures of 10a and 10d were established by X-ray crystallography. In the case of diazodiphenylmethane (8f), the initial cycloadduct 9f decomposed via a ‘twofold extrusion’ of N2 and S to give 1,1′-(2,2-diphenylethenylidene)bis[1H-imidazole] (11; Scheme 3).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19980810108
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  • 17
    Electronic Resource
    Electronic Resource
    1,3-Oxathiole and Thiirane Derivatives from the Reactions of Azibenzil and α-diazo amides with thiocarbonyl compounds (1998)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 81 (1998), S. 285-302 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of α-diazo ketones 1a,b with 9H-fluorene-9-thione (2f) in THF at room temperature yielded the symmetrical 1,3-dithiolanes 7a,b, whereas 1b and 2,2,4,4-tetramethylcyclobutane-1,3-dithione (2d) in THF at 60° led to a mixture of two stereoisomeric 1,3-oxathiole derivatives cis- and trans-9a (Scheme 2). With 2-diazo-1,2-diphenylethanone (1c), thio ketones 2a-d as well as 1,3-thiazole-5(4H)-thione 2g reacted to give 1,3-oxathiole derivatives exclusively (Schemes 3 and 4). As the reactions with 1c were more sluggish than those with 1a,b, they were catalyzed either by the addition of LiClO4 or by Rh2(OAc)4. In the case of 2d in THF/LiClO4 at room temperature, a mixture of the monoadduct 4d and the stereoisomeric bis-adducts cis- and trans-9b was formed. Monoadduct 4d could be transformed to cis- and trans-9b by treatment with 1c in the presence of Rh2(OAc)4 (Scheme 4). Xanthione (2e) and 1c in THF at room temperature reacted only when catalyzed with Rh2(OAc)4, and, in contrast to the previous reactions, the benzoyl-substituted thiirane derivative 5a was the sole product (Scheme 4). Both types of reaction were observed with α-diazo amides 1d,e (Schemes 5-7). It is worth mentioning that formation of 1,3-oxathiole or thiirane is not only dependent on the type of the carbonyl compound 2 but also on the α-diazo amide. In the case of 1d and thioxocyclobutanone 2c in THF at room temperature, the primary cycloadduct 12 was the main product. Heating the mixture to 60°, 1,3-oxathiole 10d as well as the spirocyclic thiirane-carboxamide 11b were formed. Thiirane-carboxamides 11d-g were desulfurized with (Me2N)3P in THF at 60°, yielding the corresponding acrylamide derivatives (Scheme 7). All reactions are rationalized by a mechanism via initial formation of acyl-substituted thiocarbonyl ylides which undergo either a 1,5-dipolar electrocyclization to give 1,3-oxathiole derivatives or a 1,3-dipolar electrocyclization to yield thiiranes. Only in the case of the most reactive 9H-fluorene-9-thione (2f) is the thiocarbonyl ylide trapped by a second molecule of 2f to give 1,3-dithiolane derivatives by a 1,3-dipolar cycloaddition.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19980810209
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  • 18
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    Electronic Resource
    Synthesis of Glycosylphosphine Oxides and Related Compounds (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 94-112 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The benzyl-protected glycosyl acetates 1, 6, 11, and 15 react with MeOPPh2 under catalysis by TMSOTf to yield diastereoselectively the glycosylphosphine oxides 2, 3, 8, 12, 13, and 16, with a strong preference for the 1,2-cis-configurated anomers. Hydrogenolysis of the major products gave the crystalline, unprotected phosphine oxides 4, 9, 14, and 17, of which 4 was transformed in to the acetate 5, and 9 into the benzoate 10. The benzylated phosphine oxides 4, 8, 12, and 16 were reduced with Cl3SiH in the presence of a tertiary amine to form the phosphines 18, 21, 24, and 26, which were transformed into the phosphine sulfides 19, 22, 25, and 27. Moreover, 18 and 21, were characterized as the borane adducts 20, and 23. The structure of the (arabinofuranosyl)phosphine oxide 12, the corresponding sulfide 25, and of the borane complex 20 were established by X-ray analysis. According to NMR spectroscopy, the equatorial pyranosylphosphine oxide 8, the sulfide 22, and the borane complex 23 adopt a 4C1 conformation. The axial phosphine oxide 2 is a flattened 4C1, the sulfide 19 exists as a B2,5, and the borane complex 20 is a flattened 4C1 in the solid sate and a B2,5 in solution. Thus, the conformational behavior of these α-D-glucopyranose derivatives reflects the steric requirement of the P-substituents.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760104
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  • 19
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    Electronic Resource
    Ringerweiterung von 1,2-Thiazol-3(2H)-on-1,1-dioxiden und 3-Amino-2H-azirinen zu 4H-1,2,5-Thiadiazocin-6-on-1,1-dioxiden (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 1002-1010 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring Enlargement of 1,2-Thiazol-3(2H)-one-1,1-dioxides and 3-Amino-2H-azirines to 4H-1,2,5-Thiadiazocin-6-one-1,1-dioxidesReaction of 3-amino-2H-azirines 2 with the 1,1-dioxides 4 and 7 of 1,2-thiazol-3(2H)-ones and 1,2-thiazoli-din-3-ones, respectively, in i-PrOH at room temperature leads to 4H-1,2,5-thiadiazocin-6(5H)-one-1,1-dioxides 5 (Scheme 2, Table) and the corresponding 7,8-dihydro derivatives 8 (Scheme 4), respectively. The structure of some of the new 8-membered heterocycles as well as the structure of the minor by-product 6 (Scheme 3) have been established by X-ray crystallography (Chapt. 4). The proposed reaction mechanism for the ring expansion to 5 and 8 (Scheme 2) is in accordance with previously published results of reactions of 2 and NH-acidic heterocycles and is further supported by the results of the reaction of 4a and the (1-15N)-labelled aminoazirine 2a*.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740511
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  • 20
    Electronic Resource
    Electronic Resource
    New Polycyclic Compounds from Photochemical Rearrangements of Some Substituted 2-Azatricyclo[5.2.2.01,5]undeca-4,8,10-trien-3-ones (1991)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 74 (1991), S. 1011-1026 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The products formed on UV irradiation of several tricyclic compounds (i.e. 3, 6, 8, 15, and 17, Schemes 2-4) were studied in detail. A marked dependence of the reaction course on the type and site of substitution was found. Among the several light-induced transformations, a novel rearrangement, i.e. 11 to 9 (Scheme 3) was identified. The formation of the polycyclic compound 13 on irradiation of 8a (Scheme 3) resulted from an unexpected skeletal rearrangement with dearomatization of one benzene ring. The structures of compounds 10, 11, and 13 were established by X-ray crystallography (Figs. 1-3). An attempt was made to give a general mechanistic picture of all observed photochemical results (Schemes 4-6).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19910740512
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