Patent ID: 7439344
Filing Date: 2008-10-21
Classification: C07H

Abstract:
1. A process for the selective O-acylation of a nucleoside I to afford a O-acyl nucleoside II under basic reaction conditions wherein: A is A1, A2 or A3 R R R R which process comprises the steps of: (i) dissolving I and DMAP in an heterogeneous aqueous solvent mixture and adding aqueous base to adjust the pH from 7 to 13; (ii) optionally adding sufficient saturated aqueous NaCl to produce a biphasic reaction mixture; (iii) adding an acylating agent and additional base sufficient to maintain the pH from 7 to 13; (iv) monitoring the reaction and discontinuing addition of said acylating agent and said base when the conversion reaches a satisfactory level; (v) optionally contacting the O-acyl nucleoside with a pharmaceutically acceptable acid to permit isolation of an acid additional salt of the O-acyl nucleoside.