Substituent Effect on Ring-Opening Polymerization of Regioselectively Acylated α- d -Glucopyranose 1,2,4-Orthopivalate Derivatives

To investigate the substituent effects at the 3- O and 6- O positions on ring-opening polymerization, 3,6-di- O -benzyl-α- d -glucopyranose 1,2,4-orthopivalate ( 1 ), 3- O -benzyl-6- O -pivaloyl-α- d -glucopyranose 1,2,4-orthopivalate ( 2 ), 6- O -benzyl-3- O -pivaloyl-α- d -glucopyranose 1,2,4-orthopivalate ( 3 ), and 3,6-di- O -pivaloyl-α- d -glucopyranose 1,2,4-orthopivalate ( 4 ) were selected as starting monomers and were polymerized under various reaction conditions. It was concluded from the results of monomer 1 reported previously and from those of monomers 2 − 4 in our present study that the benzyl group at the 3- O position is indispensable for yielding stereoregular (1→4)-β- d -glucopyranan derivatives, i.e., cellulose derivatives. The mechanisms of ring-opening polymerizations are discussed.