SYNTHESIS OF BENZYL TETRA-O-ACETYL-alpha-L-GLUCOPYRANOSIDE FROM BENZYL 2,3-DIDEOXY-beta-D-ERYTHRO-HEX-2-ENOPYRANOSIDE

摘要

Benzyl tetra-O-acetyl-alpha-L-glucopyranoside was synthesized from benzyl 2,3-dideoxy-beta-D-erythro-hex-2-enopyranoside in six steps and 19 overall yield. Epoxidation from the beta-side of the double bond between C-2 and C-3 of the starting material along with the subsequent regioselective ring opening by the backside attack of a hydroxide ion at C-3 furnished an intermediate with D-ido-stereochemistry. The inversion at C-5 was performed by an epimerization, by way of an N-cyclohexylenamine, after the chemoselective oxidation at primary hydroxy group of the C-6 to an aldehyde. The present synthesis of L-glucose derivatives implies the sequential stereochemical inversion of C-2 to C-5 of D-glucose. As the present synthesis keeps the whole skeleton and the order of carbon atoms based on the original numbering of D-glucose, it would work well for the synthesis of specifically labeled derivatives, beginning from isotopically labeled D-glucoses.