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Reaction of 1,3-thiazole-5(4H)-thiones with 1,2-epoxycycloalkanes: formation of spirocyclic 1,3-oxathiolanes


Blagoev, Milen; Linden, Anthony; Heimgartner, Heinz (1999). Reaction of 1,3-thiazole-5(4H)-thiones with 1,2-epoxycycloalkanes: formation of spirocyclic 1,3-oxathiolanes. Helvetica Chimica Acta, 82:1458-1469.

Abstract

Treatment of solutions of 1,3-thiazole-5(4H)-thiones 1 in CH2Cl2 at room temperature with BF3 .Et2O and 1,2-epoxycyclohexane (7-oxabicyclo[4.1.0]heptane; 2a) or 1,2-epoxycyclopentane (6-oxabicyclo[3.1.0]hexane; 2b) yielded mixtures of diastereoisomeric spirocyclic 1,3-oxathiolanes (3/4 and 8/9, respectively). In addition, the corresponding 1,3-dithiolane 6 was formed as a minor product in the reaction of 4,4-dimethyl-2-phenyl-1,3-thiazole-5(4H)-thione (1a) with 2a. The structures of the different types of products have been established by X-ray crystal-structure analysis. An ionic two-step mechanism via nucleophilic ring-opening of the complexed oxirane by the attack of the thiocarbonyl S-atom is proposed. This proposal is supported by the formation of the propellane 10 with a Wagner-Meerwein rearrangement as the key step.

Abstract

Treatment of solutions of 1,3-thiazole-5(4H)-thiones 1 in CH2Cl2 at room temperature with BF3 .Et2O and 1,2-epoxycyclohexane (7-oxabicyclo[4.1.0]heptane; 2a) or 1,2-epoxycyclopentane (6-oxabicyclo[3.1.0]hexane; 2b) yielded mixtures of diastereoisomeric spirocyclic 1,3-oxathiolanes (3/4 and 8/9, respectively). In addition, the corresponding 1,3-dithiolane 6 was formed as a minor product in the reaction of 4,4-dimethyl-2-phenyl-1,3-thiazole-5(4H)-thione (1a) with 2a. The structures of the different types of products have been established by X-ray crystal-structure analysis. An ionic two-step mechanism via nucleophilic ring-opening of the complexed oxirane by the attack of the thiocarbonyl S-atom is proposed. This proposal is supported by the formation of the propellane 10 with a Wagner-Meerwein rearrangement as the key step.

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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:1999
Deposited On:05 Nov 2013 16:36
Last Modified:28 Jul 2017 16:32
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Swiss National Science Foundation, F. Hoffmann-La Roche AG, Basel
Publisher DOI:https://doi.org/10.1002/(SICI)1522-2675(19990908)82:9<1458::AID-HLCA1458>3.0.CO;2-G

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