Process for the preparation of (3- (2 (R) - ((1R) -1- (3,5-bis (trifluoromethyl) phenyl) ethoxy) -3 (s) - (4-fluorophenyl) morpholin-4- yl) methyl) -5-oxo-4,5-dihydro- (1,2,4) triazol-1-yl) phosphonic acid.

A process for preparing a compound of formula I: or a pharmaceutically acceptable salt thereof, comprising: preparation, isolation and subsequent catalytic reduction of a compound of formula II: wherein Bn is benzyl, optionally in the presence of the counterion of a salt pharmaceutically acceptable, to give the compound of formula I, or a pharmaceutically acceptable salt thereof.