Intramolecular vinylation of carbanions using N-acyl benzomorpholines as masked vinylureas and vinylcarbamates |
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Institution: | 1. Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands;2. School of Chemistry, University of Bristol, Cantock''s Close, Bristol BS8 1TS, United Kingdom |
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Abstract: | Treatment of urea or carbamate derived benzomorpholines with lithium diisopropylamide generates N-vinyl ureas or N-vinyl carbamates by elimination of a phenoxide anion, cleaving the benzomorpholine ring. Simultaneous formation of a carbanion α to a stabilising aryl or nitrile group allows migration of the newly formed N-vinyl substituent to the carbanionic centre, in some cases with high enantiospecificity. Mild hydrolysis of the resulting urea or carbamate returns a C-vinylated amine, alcohol or hydantoin, in some cases with high enantiomeric purity. This ‘masked’ vinylation strategy avoids the need to use the reactive and volatile vinyl isocyanate as a starting material. |
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Keywords: | Vinylation Benzomorpholine Benzylic anions Tertiary stereocentre Hydantoin |
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