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Chemoselectivity of the [2+3]-Cycloaddition of Thiocarbonyl Ylides with 5-Benzylidene-3-phenylrhodanine


Seyfried, M S; Linden, A; Mloston, G; Heimgartner, H (2006). Chemoselectivity of the [2+3]-Cycloaddition of Thiocarbonyl Ylides with 5-Benzylidene-3-phenylrhodanine. Polish Journal of Chemistry, 80(8):1363-1376.

Abstract

Reactions of three different thiocarbonyl S-methylides, generated from thiobenzophenone (2), 2,2,4,4-tetramethyl-3-thioxocyclobutanone (3), and adamantanethione (8), respectively, and diazomethane, with 5-benzylidene-3-phenylrhodanine (12) were carried out. The aromatic thiocarbonyl ylide 1a adds chemoselectively to the C,C-double bond, but the spirocyclic 1,3-dithiolane 18, i.e. the [2+3]-cycloadduct with the C=S group of 12,was also formed as a minor product. In the cases of the aliphatic thiocarbonyl ylides 6 and 20, the [2+3]-cycloaddition occurred at the exocyclic C,C-double bond exclusively to give the spirocyclic tetrahydrothiophene derivatives 23 and 21, respectively. A smooth acid-catalyzed decomposition of 18 yielded the 2-diphenylmethylidene derivative 19. The formation of product 24, which was obtained in the reaction of the sterically congested ylide 6 with 12, is explained by a 1,4-H-shift in an intermediate zwitterionic adduct. The structures of the tetrahydrothiophenes 17, 21 and 23, as well as that of 24, were established by X-ray crystallography.

Abstract

Reactions of three different thiocarbonyl S-methylides, generated from thiobenzophenone (2), 2,2,4,4-tetramethyl-3-thioxocyclobutanone (3), and adamantanethione (8), respectively, and diazomethane, with 5-benzylidene-3-phenylrhodanine (12) were carried out. The aromatic thiocarbonyl ylide 1a adds chemoselectively to the C,C-double bond, but the spirocyclic 1,3-dithiolane 18, i.e. the [2+3]-cycloadduct with the C=S group of 12,was also formed as a minor product. In the cases of the aliphatic thiocarbonyl ylides 6 and 20, the [2+3]-cycloaddition occurred at the exocyclic C,C-double bond exclusively to give the spirocyclic tetrahydrothiophene derivatives 23 and 21, respectively. A smooth acid-catalyzed decomposition of 18 yielded the 2-diphenylmethylidene derivative 19. The formation of product 24, which was obtained in the reaction of the sterically congested ylide 6 with 12, is explained by a 1,4-H-shift in an intermediate zwitterionic adduct. The structures of the tetrahydrothiophenes 17, 21 and 23, as well as that of 24, were established by X-ray crystallography.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2006
Deposited On:22 May 2012 06:30
Last Modified:07 Dec 2017 11:02
Publisher:Polskie Towarzystwo Chemiczne
ISSN:0137-5083
Funders:Swiss National Science Foundation, F. Hoffmann-La Roche AG, Basel, Polish State Committee for Scientific Research
Related URLs:http://www.ichf.edu.pl/pjch/pj-2006/pj-2006-08c.htm

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