Stereospecific Synthesis of<i>N</i>-(Diphenylmethylene)-α,β-didehydroamino Acid Methyl Esters from β-Hydroxy-α-amino Acids

Abstract

N-(Diphenylmethylene)-α,β-didehydroamino acid methyl esters 2b-d are prepared with absolute geometric selectivity from inexpensive β-hydroxyamino acids through the intermediates N-(diphenylmethylene)- β-hydroxyamino acid methyl esters 1b-d. Besides, an easy conversion from E isomers to the corresponding Z isomers was performed, thus avoiding the use of the uncommon allo-β-hydroxyamino acids as starting materials.