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lntramolekulare 1,3-dipolare Cycloadditionen mit alkenyl-substituierten 3,4-Diarylsydnonen


Meier, Hansruedi; Heimgartner, Heinz (1986). lntramolekulare 1,3-dipolare Cycloadditionen mit alkenyl-substituierten 3,4-Diarylsydnonen. Helvetica Chimica Acta, 69(4):927-940.

Abstract

The 3,4-diarylsydnones 1 and 12a-e with an allyl or alkenyloxy substituent on the N(3)-phenyl group have been synthesized by classical methods starting from 2-allylaniline and the corresponding alkenyloxyanilines, respectively (Schemes 2 and 3). Whereas the allyl-substituted sydnone 1 undergoes an intramolecular 1,3-dipolar cyclodddition at room temperature in solution to yield 13 (Scheme 4), the alkenyloxy-substituted sydnones 12a-e are thermally stable. On irradiation of 1 and 12a-d, formation of the fused dihydropyrazoles 2 and 14a-d (Schemes 1 and 5) is observed. In the case of 12d, the yield of 14d is very low, and the symmetric 1,2,3-triazole 15a has been isolated as the main product. A very likely reaction mechanism for the formation of the photoproducts involves decarboxylation of the sydnones to give a nitrile-imine which undergoes an intramolecular 1,3-dipolar cycloaddi- tion onto the C=C bond.

Abstract

The 3,4-diarylsydnones 1 and 12a-e with an allyl or alkenyloxy substituent on the N(3)-phenyl group have been synthesized by classical methods starting from 2-allylaniline and the corresponding alkenyloxyanilines, respectively (Schemes 2 and 3). Whereas the allyl-substituted sydnone 1 undergoes an intramolecular 1,3-dipolar cyclodddition at room temperature in solution to yield 13 (Scheme 4), the alkenyloxy-substituted sydnones 12a-e are thermally stable. On irradiation of 1 and 12a-d, formation of the fused dihydropyrazoles 2 and 14a-d (Schemes 1 and 5) is observed. In the case of 12d, the yield of 14d is very low, and the symmetric 1,2,3-triazole 15a has been isolated as the main product. A very likely reaction mechanism for the formation of the photoproducts involves decarboxylation of the sydnones to give a nitrile-imine which undergoes an intramolecular 1,3-dipolar cycloaddi- tion onto the C=C bond.

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Additional indexing

Other titles:Intramolecular 1,3-Dipolar Cycloaddition Reactions of Alkenyl-substituted 3,4-Diarylsydnones
Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:German
Date:1986
Deposited On:03 Jun 2014 07:07
Last Modified:05 Apr 2016 17:54
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung, F. Hoffmann-La Roche & Co. AG, Basel
Publisher DOI:https://doi.org/10.1002/hlca.19860690421

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