Solvent-free synthesis of enantioenriched ß-silyl nitroalkanes under organocatalytic conditions.

ABSTRACT

An enantioselective 1,4-conjugate addition of nitromethane to ß-silyl α,ß-unsaturated carbonyl compounds catalyzed by bifunctional squaramide catalysts has been developed. This methodology offers both enantiomers of ß-silyl nitroalkanes in good to excellent yields (up to 92%) and enantioselectivities (up to 97.5% ee) under solvent-free conditions at room temperature. Control experiments reveal that the presence of a ß-silyl group in the enones is crucial for high reactivity under the optimized reaction conditions.