SELECTIVE RING-OPENING POLYMERIZATION OF DI-O-METHYLATED AND DI-O-BENZYLATED 1,4-ANHYDRO- alpha -D-RIBOPYRANOSES AND STRUCTURE PROOF OF SYNTHETIC CELLULOSE-TYPE POLYSACCHARIDE (1 yields 4)- BETA -D-RIBOPYRANAN AND (1 yields 5)- alpha -D-RIBOFURANAN.

Article abstract of DOI:10.1021/ja00361a021

The cationic polymerization of 1,4-anhydro-2,3-di-O-methyl- alpha -D-ribopyranose (ADMR) for the first time gave two kinds of stereoregular polysaccharide derivatives, 2,3-di-O-methyl-(1 yields 4)- BETA -D-ribopyranan and 2,3-di-O-methyl-(1 yields 5)- alpha -D-ribofuranan, by selective ring-opening polymerization with phosphorus pentafluoride as catalyst at low temperatures. The latter polymer was prepared by boron trifluoride etherate and other relatively weak Lewis acids as catalyst. In addition, the polymerization of 1,4-anhydro-2,3-di-O-benzyl- alpha -D-ribopyranose by various Lewis acids as catalyst provided stereoregular 2,3-di-O-benzoyl-(1 yields 5)- alpha -D-ribofuranan by the selective 1,5-ring scission. The 2,3-di-O-benzyl-(1 yields 5)- alpha -D-ribofuranan was debenzylated to give a new stereoregular polysaccharide (1 yields 5)- alpha -D-ribofuranan.