Patent ID: 6632940
Filing Date: 2003-10-14
Classification: C07H

Abstract:
A method of preparing laminaribiose comprising a step of glycosidic coupling between a glycosyl donor and a glycosyl acceptor, wherein:the glycosyl donor is in pyranose form and is of formula (II): â€ƒin which: R1 represents: an alkyl or haloalkyl radical having 1 to 6 carbon atoms; an aryl radical which is non-substituted or substituted with one or more groups selected from the group consisting of a halogen atom, an alkoxy radical having 1 to 6 carbon atoms and a nitro group; X represents an electrophilic leaving group selected from the group consisting of: a group of formula S(O)nRâ€² in which Râ€² represents a radical selected from the group consisting of an alkyl radical having 1 to 6 carbon atoms, an aryl radical which is non-substituted or substituted with an alkoxy group having 1 to 6 carbon atoms, a nitro and acetamide group, and n is an integer equal to 0 or 1 and; a trichloroacetimidate group; the glycosyl acceptor is in furanose form and is of formula (III) â€ƒin which: R2 and R3 together form a radical selected from the group consisting of a methylidyl, ethylidyl, trichloroethylidyl, isopropylidyl, hexafluoroisopropylidyl, cyclopentylidyl, cyclohexylidyl, cycloheptylidyl, butylidyl, 1-tert-butylethylidyl, 1-phenylethylidyl, benzylidyl, methoxybenzylidyl, and 1-phenylbenzylidyl radical; and R4 and R5 together form a radical selected from the group consisting of a methylidyl, ethylidyl, trichloroethylidyl, isopropylidyl, hexafluoroisopropylidyl, cyclopentylidyl, cyclohexylidyl, cycloheptylidyl, butylidyl, 1-tert-butylethylidyl, 1-phenylethylidyl, benzylidyl, methoxybenzylidyl, or 1-phenylbenzylidyl radical; or independently represent a benzyl, acetyl, benzoyl chlorobenzoyl, methoxybenzoyl, nitrobenzoyl, allyl, chlorobenzyl, methoxybenzyl and nitrobenzyl radical; said coupling step is carried out in solution in an anhydrous organic solvent, at a temperature between âˆ’80Â° C. and 40Â° C., for a period of 1 minute to 8 hours, in the presence of a suitable promoter selected from the group consisting of: N-bromosuccinimide or N-iodosuccinimide, combined with a Lewis acid selected from the group consisting of ferric chloride, copper ditriflate, tin ditriflate, boron trifluoride dietherate, tin or zirconium tetrachloride, methyl triflate, trimethyl- (or triethyl-) silyl triflate, silver triflate, cadmium ditriflate, cobalt ditriflate, nickel ditriflate, zinc ditriflate, bismuth tritriflate, iron tritriflate, and gallium tritriflate, in the case in which X represents an S(O)nRâ€² group as defined above in which n is equal to 0, a Lewis acid selected from the group consisitng of triflic anhydride, ferric chloride, copper ditriflate, tin ditriflate, boron trifluoride dietherate, tin or zirconium tetrachloride, methyl triflate, trimethyl- (or triethyl-) silyl triflate, silver triflate, cadmium ditriflate, cobalt ditriflate, nickel ditriflate, zinc ditriflate, bismuth tritriflate, iron tritriflate, and gallium tritriflate, combined with an amine, in the case in which X represents an S(O)nRâ€² group as defined above in which n is equal to 1, and a Bronsted acid or a Lewis acid selected from the group consisting of triflic anhydride, ferric chloride, copper ditriflate, tin ditriflate, boron trifluoride dietherate, tin or zirconium tetrachloride, methyl triflate, trimethyl- (or triethyl-) silyl triflate, silver triflate, cadmium ditriflate, cobalt ditriflate, nickel ditriflate, zinc ditriflate, bismuth tritriflate, iron tritriflate, and gallium tritriflate, in the case in which X represents a trichloroacetimidate group; and the reaction product thus obtained, neutralised and purified, being subjected to a deprotection treatment to give, after purification, laminaribiose.