Regioselective pivaloylation of N-phthaloylchitosan: a promising soluble intermediate for chitosan chemistry.

A simple and efficient pivaloylation of primary alcohols was realized on N-phthaloylchitosan that was regioselectively and entirely protected. The selectivity of this mild esterification was demonstrated by comparison with (1)H NMR chemical shifts of H-1 and H-3 of complete 3,6-O-dipivaloylated derivatives. The selective hydrazinolysis of N-phthaloyl groups in the presence of pivaloyl ester was achieved in ethanol/water.