Process for the preparation of naproxene nitroxyalkylesters

A process for obtaining nitroxyalklesters of the 2(S)(6-methoxy-2-naphthyl)-propanoic acid having an enantiomeric excess higher than or equal to 95%, preferably higher than or equal to 98%, characterized in that an halide of the 2-(S)-(6 methoxy-2-naphthyl)propanoic acid of formula A-Hal, wherein A is the acid acyl residue, is reacted in an inert organic solvent with an aliphatic nitroxyalkanol HO—Y—ONO 2 , wherein Y is a C 2 -C 20 alkylene or a cycloalkylene from 3 to 8 carbon atoms, or an alkylene as defined containing a cycloalkylene as defined, in the presence of an inorganic base.