Regioselectively modified stereoregular polysaccharides, 12. Synthesis of (1→6)‐α‐linked polysaccharides consisting of D ‐glucose and 2,3,4‐tri‐O‐octadecyl‐ D ‐glucose units

By ring‐opening copolymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐octadecyl‐β‐D‐glucopyranose (1) with 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranose (2) using phosphorus pentafluoride as initiator in dichloromethane at 0°C, stereoregular copolymers 3, with M̄n = 6 · 103 to 24 · 103 were obtained. For debenzylation of copolymers 3, either the reduction with sodium in liquid ammonia or radical bromination‐hydrolysis was applied, depending on solubility and copolymer composition. Poly[2,3,4‐tri‐O‐octadecyl‐α‐D‐glucopyranosyl‐(1→6)‐stat‐α‐D‐glucopyranosyl‐(1→6)] (4,) exhibits characteristic solution properties arising from its amphiphilic structure. Polysaccharide 4, with mole fractions of trioctadecylated unit (x) below 0,03, are water‐soluble and interact with magnesium 1‐anilino‐8‐naphthalenesulfonate (ANS) in water. The polysaccharide 4 (x = 0,29), which is soluble in chloroform, was found to solubilize an aqueous methyl orange solution in chloroform. Formation of micelles in water and reversed micelles in chloroform is suggested.