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[2+3] Cycloadditions of ‘Thiocarbonyl Ylides’ (= (Alkylidenesu1fonio)methanides) and Diazoalkanes with N,N’-(Thiocarbony1)diimidazole ( = 1’1’-(Carbonothioyl)bis[lH-imidazolej)


Mloston, Grzegorz; Gendek, Tomasz; Linden, Anthony; Heimgartner, Heinz (1998). [2+3] Cycloadditions of ‘Thiocarbonyl Ylides’ (= (Alkylidenesu1fonio)methanides) and Diazoalkanes with N,N’-(Thiocarbony1)diimidazole ( = 1’1’-(Carbonothioyl)bis[lH-imidazolej). Helvetica Chimica Acta, 81(1):66-77.

Abstract

Heating of a mixture of N,N-(thiocarbony1)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).

Heating of a mixture of N,N-(thiocarbony1)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).

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Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:1998
Deposited On:12 Nov 2013 14:10
Last Modified:05 Apr 2016 17:07
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Polish State Committee for Scientific Research, Swiss National Science Foundation, F. Hoffmann-La Roche AG, Basel
Publisher DOI:https://doi.org/10.1002/hlca.19980810108
Permanent URL: https://doi.org/10.5167/uzh-84634

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