RING-OPENING POLYMERIZATION OF NEW 1,6-ANHYDRO-BETA-D-GLUCOSAMINE DERIVATIVES

New 1,6-anhydro-glucosamine monomers having amino protecting groups at C2 positions; i.e. thylsilyl)ethylamino)-2-deoxy-beta-D-glucopyranose (A2NSG), -2-hexamethyleneimino-2-deoxy-beta-D-glucopyranose (A2NHG) a nd 1,6-anhydro-3,4-di-O-benzyl-2- (N,N-dibenzylamino)-2-deoxy-beta-D-g lucopyranose (A2NBG), were synthesized in order to investigate the eff ects of the 2-amino groups on cationic ring-opening polymerizations. W hen phosphorus pentafluoride and antimony pentachloride were used as i nitiators, the A2NSG monomer gave polymers having number-average molec ular weights of (M) over bar n = 4.1 X 10(3) and 3.4 X 10(3) ((P) over bar D-n = 13 and 8), respectively. The resulting polymers had positiv e specific rotations ranging from [alpha](D)(25) + 33.1 degrees to + 4 4.1 degrees and the C1 signal in the C-13 NMR spectra appeared as a si ngle peak around 100 ppm, which suggested that the polymers had 1,6-al pha stereoregularity. The A2NHG monomer gave polymers in low yields, a nd the A2NBG monomer had no polymerizability. These results suggest th at the ring-opening polymerization of 1,6-anhydro-glucosamine monomers depends on both electron withdrawal and steric hindrance of the 2-ami no protecting groups. (C) 1998 Elsevier Science Ltd. All rights reserv ed.