Synthesis of Enantiomerically Pure (1S,2S)-1-Aminocyclopropanephosphonic Acids from (2S)-Methylcyclopropanone Acetal

Abstract

A one-pot reaction of methylcyclopropanone acetal (2S)-4b with chiral amines and a trialkyl phosphite has been devised, by means of which the amino phosphonate esters 8 are obtained with excellent diastereoselectivities. Catalytic hydrogenolysis and hydrolysis of these phosphonates gives (1S,2S)-1-amino-2-methylcyclopropanephosphonic acid 1b in good overall yield and with excellent enantiomeric excess.