Highly Regio- and Enantioselective Organocatalytic Conjugate Addition of Alkyl Methyl Ketones to a β-Silylmethylene Malonate
作者:Raghunath Chowdhury、Sunil K. Ghosh
DOI:10.1021/ol900803n
日期:2009.8.6
(S)-N-(2-Pyrrolidinylmethyl)pyrrolidine/trifluoroacetic acid (3:1) combination catalyzed the direct addition of alkyl methyl ketones to β-dimethyl(phenyl)silylmethylene malonate at the methyl terminal with high yield and excellent regio- and enantioselectivity. The silyl group played crucial roles in regioselection and substrate reactivity.
Benzyne and 1-naphthyne (generated from the corresponding halogeno derivatives and the Complex Base NaNH2-ButONa) condense with α,β-unsaturated ketone enolates β-substituted by an aromatic ring and only enolisable in the α'-position, to lead to α-tetralones and/or indanones. The reaction path depends upon the nature of the ketone enolate and, less strongly, on the solvent. The reaction mechanism is