Enantioselective reduction of ketophosphonates using adducts of chiral natural acids with sodium borohydride

Abstract

A method for asymmetric reduction of α- and β-ketophosphonates using chiral complexes prepared from sodium borohydride and natural aminoacids or tartaric acids was developed. Reduction of α or β-ketophosphonates by these reagents led to formation of chiral (S)- or (R)- hydroxyphosphonates. Reduction of chiral di-(1R,2S,5R)-menthylketophosphonates by the chiral complexes NaBH4/(R,R)-proline or NaBH4/(R,R)-tartaric acid due to the double matched asymmetric induction resulted in increased stereoselectivity of the reaction and led to the formation of hydroxyphosphonates up to 90% ee or higher. Dimenthyl 2-hydroxy-3- chloropropylphosphonate was utilized as a chiron for the preparation of a number of biologically active compounds in multigram quantity. ©ARKAT-USA, Inc.