Direct asymmetric intramolecular alkylation of beta-alkoxy-alpha-amino esters via memory of chirality

The intramolecular alpha-alkylation of beta-alkoxy-alpha-amino esters derived from L-serine proceeded predominantly over beta-elimination. When beta-alkoxy-alpha-amino esters were treated with powdered CsOH in DMSO at 20 degrees C, alpha-alkoxymethyl cyclic amino esters were obtained in up to 94% ee. Optically active THF amino acids were synthesized for the first time by the present method.