Asymmetric synthesis of alpha-methyl alpha-amino acids through diastereoselective alkylation under mild reaction conditions of an iminic alanine template with a 1,2,3,6-tetrahydro-2-pyrazinone structure

(6R)-6-Isopropyl-3-methyl-5-phenyl-1,2,3,6-tetrahydro-2-pyrazinone, obtaine d from (R)-valine and (S)-alanine, is highly diastereoselectively alkylated at room temperature by: a) activated alkyl halides under solid-liquid PTC conditions, b) non-activated alkyl halides with organic bases, c) electroph ilic olefins employing both solid-liquid PTC conditions and organic bases, and d) allylic carbonates by means of palladium catalysis under neutral con ditions. Enantiomerically pure (S)-alpha-methyl alpha-amino acids 8 are obt ained by hydrolysis of the alkylated pyrazinones.