Reactions of azide ion with 2-O-trifluoromethanesulphonates of both 34:67-di-O-isopropylidene-D-glycero-D-talo-hepton-0-15-lactone and of 34;67-di-O-isopropylidene-D-glycero-D-galacto-heptono-1-5-lactone give predominantly 2-azido-2-deoxy-3 4:6 7-di-O-isopropylidene-D-glycero-D-galacto 5-lactone initially which then isomerises under the reaction conditions to 2-azido-2-deoxy-34:67-di-O-isopropylidene-Dglycerol-D-talo-heptono-1 X-ray crystal structure analyses of 34;67-di-O-isopropylidene-D-glyceroD-1-talo-heptono-1 5-lactone. and 2-azido-2-deoxy-3 4:6 7-di-O-isopropylidene-D-glycero-D-talo-heptono-15-lactone are reported. © 1990.
