Chloroform → HCID 86738946, Verbindung

A solution of 0.51 g (2 mmol) of the intermediate VIII in 10 ml of acetic acid and 40 ml of water was heated at 100° C. for two hours, then evaporated to dryness to give 2,3,4,6-tetradeoxy-4-C-methylene-3-trifluoroacetamido-L-threo-hexopyranose (IX, 0.47 g, 99%) as a white solid: m.p. 168°-170° C., [α]D20° -160° (c=0.5, CHCl3). Treatment of IX (0.36 g, 1.5 mmol) in 25 ml of dry methylene dichloride with 4 ml of trifluoroacetic anhydride for 2 hours at 0° C. and 1 hour at 20° C. gave, after evaporation, the 1-0-trifluoroacetate (X), which was directly used for the preparation of the corresponding 1-chloro-derivative by treatment with dry hydrogen chloride in anhydrous diethyl ether at 0° C. After standing at 0° C. overnight, the reaction mixture was evaporated to dryness to give 2,3,4,6-tetradeoxy-4-C-methylene-3-trifluoroacetamido-L-threo-hexopyranosyl chloride (III-A, 0.35 g, 90%), suitable for the subsequent coupling reaction without further purification.