ACTION OF BROMINE ON TETRA-0-ACETYL-1-S-ACETYL-1-THIO-BETA-D-GLUCOPYRANOSE . FORMATION AND DECOMPOSITION OF TETRA-0-ACETYL-BETA-D-GLUCOPYRANOSYLSULFENYL BROMIDE

Treatment of either tetra-O-acetyl-1-S-acetyl-1-thio-β-D-glucopyranose (1) or tert-butyl tetra-O-acetyl-1-thio-β-D-glucopyranoside (6) with a >3-molar excess of bromine in carbon tetrachloride or pure chloroform, at 10° for 1-3 min, gives tetra-O-acetyl-β-D-glucopyranosylsulfenyl bromide (2) in quantitative yield; prolonged exposure to bromine at room temperature converts the product 2 into tetra-O-acetyl-α-D-glucopyranosyl bromide (3). Slow addition of bromine to the 1-thioglycoside 6 in carbon tetrachloride, or bromination of the thiolacetate 1 in reagent-grade chloroform, gives bis(tetra-O-acetyl-β-D-glucopyranosyl) disulfide (4), also obtainable by treating the sulfenyl bromide 2 with dry ethanol or with the 1-thioglycoside 6. Oxidation of the disulfide 4 with m-chloroperoxybenzoic acid gives a mono-oxide derivative 5, also obtainable by treating the sulfenyl bromide 2 with water or 95% ethanol. The disulfide 4 and its mono-oxide 5 were both converted into the bromide 3 by prolonged exposure to bromine at room temperature. © 1969.