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(Benzylthio)- und (Arylthio)-substituierte Nitril-ylide: thermische Erzeugung und Reaktionen


Wipf, Peter; Prewo, Roland; Bieri, Jost H; Germain, Gabriel; Heimgartner, Heinz (1988). (Benzylthio)- und (Arylthio)-substituierte Nitril-ylide: thermische Erzeugung und Reaktionen. Helvetica Chimica Acta, 71(5):1177-1190.

Abstract

Thermolysis of 4-(benzylthio)- and 4-(arylthio)-1,3-oxazol-5(2H)-ones 6, at 110-155° in the presence of dipolarophiles with activated C=C, C=C, C=O, C=S, and N=N bonds, led to 5-membered cyclo-adducts and CO2 (cf: Schemes 3, 5-7). Heating 6a and 6c in the presence of ethyl propiolate yielded ethyl quinoline-3-carboxylate (19) and ethyl pyridine-3-carboxylate (22), respectively (cf. Scheme 8). These results are rationalized on the basis of the intermediate formation of thio-substituted nitrile ylides of type 7 (cf. Scheme 2), which undergo regioselective 1,3-dipolar cycloadditions with reactive dipolarophiles. In the absence of such a dipolarophile, the nitrile ylides isomerize via a [1,4]-H shift to give 2-aza-1,3-butadienes of type 20. The latter are trapped in a Diels-Alder reaction with ethyl propiolate (cf. Scheme 8).

Abstract

Thermolysis of 4-(benzylthio)- and 4-(arylthio)-1,3-oxazol-5(2H)-ones 6, at 110-155° in the presence of dipolarophiles with activated C=C, C=C, C=O, C=S, and N=N bonds, led to 5-membered cyclo-adducts and CO2 (cf: Schemes 3, 5-7). Heating 6a and 6c in the presence of ethyl propiolate yielded ethyl quinoline-3-carboxylate (19) and ethyl pyridine-3-carboxylate (22), respectively (cf. Scheme 8). These results are rationalized on the basis of the intermediate formation of thio-substituted nitrile ylides of type 7 (cf. Scheme 2), which undergo regioselective 1,3-dipolar cycloadditions with reactive dipolarophiles. In the absence of such a dipolarophile, the nitrile ylides isomerize via a [1,4]-H shift to give 2-aza-1,3-butadienes of type 20. The latter are trapped in a Diels-Alder reaction with ethyl propiolate (cf. Scheme 8).

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Additional indexing

Other titles:Thermal Generation and Reactions of (Benzylthio)- and (Arylthio)-Substituted Nitrile Ylides
Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:German
Date:1988
Deposited On:14 May 2014 08:48
Last Modified:08 Dec 2017 05:19
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung, F. Hoffmann-La Roche AG, Basel
Publisher DOI:https://doi.org/10.1002/hlca.19880710529

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