AN IMPROVED PROCESS FOR THE PREPARATION OF FOSAPREPITANT HAVING IMPROVED PURITY

摘要

The present invention relates to an improved process for the preparation of [3-{[(2R,3S)-2- [(1R)-1-[3,5-bis(trifluoromethyl)phenyl]ethoxy]-3-(4-fluorophenyl)morpholin-4- yl]methyl}-5-oxo-2H-1,2,4-triazol-1-yl]phosphonic acid (Fosaprepitant or the compound of formula I) or its pharmaceutically acceptable salt, having palladium (Pd) content less than 1 ppm comprising catalytic hydrogenation of the compound of formula II with Pd catalyst optionally in the presence of base, to give the compound of formula I or the pharmaceutically acceptable salt thereof, optionally isolating the compound of formula I or the pharmaceutically acceptable salt and treating the compound of formula I or the pharmaceutically acceptable salt thereof twice with the metal scavenger to obtain the compound of formula I or the pharmaceutically acceptable salt thereof having Pd content less than 1 ppm.