REACTION OF GLYCOSYL HALIDES WITH BENZYL GRIGNARD-REAGENTS - UNEXPECTED O-TOLYL ALKYLATION OF TETRA-O-ACETYLGLUCOPYRANOSYL BROMIDE AND DIRECT SYNTHESIS OF (BETA-GLYCOSYL)PHENYLMETHANES

The synthesis of (beta-glycosyl)phenylmethanes by Grignard alkylation of glycosyl halides is investigated. Reaction of tetra-O-acetylglucopy ranosyl bromide with benzylmagnesium chloride gave a good yield of a 3 :1 mixture of 2-(beta-D-glucopyranosyl)toluene and (beta-glucosyl)phen ylmethane. The requirement for an equatorial 2-acetoxy group and 6-ace toxymethyl group for the formation of the unexpected o-tolyl rearrange ment product is explored by using xylosyl, mannosyl, and 2-deoxyglucos yl halides as substrates for the alkylation. Synthesis of (beta-glucos yl)phenylmethane by alkylation of 2,3,4,6-tetra-O-benzylglucosyl bromi de with benzylmagnesium chloride is also presented.