ENANTIOSELECTIVE SYNTHESIS OF BETA-AMINO ACIDS .4. 1,2 ASYMMETRIC INDUCTION IN THE ALKYLATION OF 1-BENZOYL-3,6(S)-DIMETHYLPERHYDROPYRIMIDIN-4-ONE - PREPARATION OF THE LIKE AND UNLIKE STEREOISOMERS OF 2-METHYL-3(S)-AMINOBUTANOIC AND 2-BENZYL-3(S)-AMINOBUTANOIC ACID

The title perhydropyrimidin-4-one (S)-4 was prepared from (S)-3-aminobutanoic acid via the Schiff base (S)-8. This heterocycle was alkylated (LDA, methyl iodide, or benzyl bromide) to afford the like and unlike diastereomeric products in a 80:20 ratio. Separation and hydrolysis (6 N aqueous HCl) of these 5,6-dialkylperhydropyrimidin-4-ones leads to the free, enantiomerically pure, amino acids 11-14.