REGIOSELECTIVE INTRODUCTION OF BETA-GALACTOSIDE BRANCHES INTO CHITOSAN AND CHITIN

beta-D-Galactoside branches have been introduced into chitosan and chi tin regioselectively through a series of controlled modification react ions based on N-phthaloyl-chitosan. The glycosylation reaction between a chitosan derivative having a reactive group only at C-6 and an orth oester of D-galactose proceeded efficiently to give a protected produc t with a degree of substitution up to about 0.5. Deprotection gave a b ranched chitosan, and the subsequent N-acetylation afforded a branched chitin. Unlike chitosan and chitin, the resulting nonnatural branched polysaccharides were characterized by high affinity for solvents and readily soluble in neutral water. Furthermore, branched chitin was eas ily degraded by lysozyme.