ASYMMETRIC ADDITION OF METHYL NITROACETATE TO CROTONALDEHYDE CATALYZED BY CHIRAL AMINES

The asymmetric Michael addition of methyl nitroacetate to crotonaldehy de catalyzed by chiral amines was carried out. The maximum chemical yi eld of diastereomeric products amounted to 95 %. The best asymmetric i nduction (42 % e.e.) was achieved in the case of catalysis by (S)-prol inol. The diastereomeric mixture was converted to a mixture of stereoi someric 3-methyl-2-methoxycarbonylpyrrolidines. Absolute configuration s of (2S,3S)- and (2R,3S)-isomers formed in excess were determined usi ng GLC by comparison with authentic samples of racemic and optically p ure forms of 3-methylproline.