Enantiomerically pure 4-amino-1,2,3-trihydroxybutylphosphonic acids

Abstract

(1 S,2 R,3 S)-, (1 R,2 R,3 S)- and (1 S,2 R,3 R)-4-amino-1,2,3-trihydroxybutylphosphonic acids were synthesised. The synthetic strategy involved preparation of the respective 4-azido-2,3- O-isopropylidene- l-threose or - d-erythrose, addition of dialkyl phosphites, separation of C-1 epimeric O, O-dibenzyl phosphonates, the reduction of azides and the removal of the protecting groups. The (2 R,3 S) and (2 R,3 R) configurations in the final products were secured by employing diethyl l-tartrate and d-isoascorbic acid as starting materials. The stereochemical course of the addition to the carbonyl groups in 4-azido-2,3- O-isopropylidene- l-threose or - d-erythrose followed that established earlier for 2,3- O-isopropylidene- d-glyceraldehyde and similar (3:1–4:1) diastereoselectivities were achieved.