Organofluorine Compounds and Fluorinating Agents. Part 21. Perfluoroalkylidene Sugars by Non-Classical Acetalation of Pyranoses.

Abstract Acetalations of methyl α- d -mannopyranoside (1), methyl 6-O-trityl-α- d -mannopyranoside (5), benzyl α- d -mannopyranoside (14), and methyl β- d -galactopyranoside (17) with perfluoroaldehydes (C4F9CH=O, C6F13CH=O, and C8F17CH=O) in the presence of dicyclohexylcarbodiimide (DCC) lead, under epimerization at the C-atom 3 of the corresponding pyranose moiety, to perfluoroalkylidene derivatives of α- d -altrosides (2–4, 6/7, 15) and of β- d -gulosides (18–20), respectively. After partial deprotection of 3 (or 15) and 18–20, respectively, the liquid crystalline, amphiphilic 3,4-O-perfluorohexylidene- d -altropyranoside (13) and 2,3-O-perfiuoroalkylidene- d -gulopyranosides 24–26 were obtained.