Substituent Effect on Ring-Opening Polymerization of Regioselectively Acylated 1,4-Anhydro-α- d -glucopyranose Derivatives

To investigate the substituent effects at the 2- O, 6- O, and 3- O positions on ring-opening polymerization, 1,4-anhydro-2,3-di- O -benzyl-6- O -pivaloyl-α- d -glucopyranose ( 1 ), 1,4-anhydro-3,6-di- O -benzyl-2- O -pivaloyl-α- d -glucopyranose ( 2 ), 1,4-anhydro-3- O -benzyl-2,6-di- O -pivaloyl-α- d -glucopyranose ( 3 ), and 1,4-anhydro-6- O -benzyl-2,3-di- O -pivaloyl-α- d -glucopyranose ( 4 ) were selected as starting monomers and were polymerized under various reaction conditions. It was concluded from the results of monomers 1 and 2 reported previously and from those of monomers 3 and 4 in our present study that both the pivaloyl group at the 2- O position and the benzyl group at the 3- O position are indispensable for yielding stereoregular (1→5)-β- d -glucofuranan derivatives with high molecular weights and that a substituent group at the 6- O position hardly affects stereoregularity or polymerizability. The 1,4-anhydro-α- d -glucopyranose skeleton is not suitable for yielding a (1→4)-β- d -glucopyranan i.e., cellulose.