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Ringöffnungen von sterisch gehinderten spirocyclischen 2,5-Dihydro- 1,3,4-thiadiazolen mit cycloaliphatischen, sekundären Aminen


Mloston, Grzegorz; Romanski, Jaroslaw; Linden, Anthony; Heimgartner, Heinz (1997). Ringöffnungen von sterisch gehinderten spirocyclischen 2,5-Dihydro- 1,3,4-thiadiazolen mit cycloaliphatischen, sekundären Aminen. Helvetica Chimica Acta, 80:230-240.

Abstract

Ring Opening of Sterically Crowded Spirocyclic 2,S-Dihydro-1,3,4-thiadiazoles by Cycloaliphatic Secondary Amines At room temperature, the spirocyclic 2,5-dihydro-1,3,4-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 10a (Scheme 3 ) was isolated as a minor product.

Ring Opening of Sterically Crowded Spirocyclic 2,S-Dihydro-1,3,4-thiadiazoles by Cycloaliphatic Secondary Amines At room temperature, the spirocyclic 2,5-dihydro-1,3,4-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 10a (Scheme 3 ) was isolated as a minor product.

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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:German
Date:1997
Deposited On:18 Nov 2013 09:55
Last Modified:05 Apr 2016 17:09
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Polnisches Nationalkomitee zur Förderung der wissenschaftlichen Forschung , Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung, F. Hoffmann-La Roche AG, Basel
Permanent URL: https://doi.org/10.5167/uzh-85033

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