REACTIONS OF FURANOSIDE EPOXIDES . PREPARATION OF BROMOHYDRINS FROM METHYL5-O-ACETYL-2,3-ANHYDRO-ALPHA(AND BETA)-D-RIBOFURANOSIDE

The reaction of anhydrous magnesium bromide with methyl 5-O-acetyl-2,3-anhydro-α-D-ribofuranoside gives a mixture of methyl 5-O-acetyl-2-bromo-2-deoxy-α-D-arabinofuranoside and methyl 5-O-acetyl-3-bromo-3-deoxy-α-D-xylofuranoside in which the latter preponderates. With methyl 5-O-acetyl-2,3-anhydro-β-D-ribofuranoside, the same reagent gives methyl 5-O-acetyl-3-bromo-3-deoxy-β-D-xylofuranoside as the only isolable product. An adjacent methoxyl group shows greater steric inhibition than an adjacent acetoxymethyl group. © 1969.