1,2-O-Trichloroethylidene acetal group protected 3,5-dieno-1,4-furanose derivatives

The preparation of 3,5-(E)-dieno-3,5,6,8-tetradeoxy-(S)-1,2-O-trichloroethylidene-α-d-glycero-octo-1,4-furano-7-ulose starting from either 1,2-O-(S)-trichloroethylidene-α-d-glucofuranose (β-chloralose) or 1,2-O-(S)-trichloroethylidene-α-d-galactofuranose (galactochloralose) and the preparation of methyl 3,5-(E)-dieno-3,5,6-trideoxy-(S)-1,2-O-trichloroethylidene-α-d-glycero-hepta-1,4-furano-uronate starting from β-chloralose are described. Endocyclic double bond formations were realised by the elimination of 3-acetoxy groups using DMF–sodium bicarbonate. This elimination was not successful when the starting compound was 1,2-O-(R)-trichloroethylidene-α-d-glucofuranose (α-chloralose), where the trichloromethyl group occupies the endo position.