Syntheses and reactions of saturated and 2,3-unsaturated vinyl and 1′-substituted-vinyl glycosides

Abstract

Reaction of tetra-O-α-d-glucopyranosyl bromide with bis(acylmethyl)mercurys [Hg (CH2COR)2] afforded acetylated vinyl [by use of bis(formylmethyl)mercury] or 1′-substituted-vinyl β-d-glucopyranosides 11-13 in high yields. When used together with phenyl 4,6-di-O-acetyl-2,3-dideoxy-1-thio-α-d-erythro-hex-2-enopyranoside, these reagents gave analogous vinyl 4,6-di-O-acetyl-2,3-dideoxy-d-erythro-hex-2-enopyranosides 20-23 which, on treatment with Lewis acids, isomerised to the corresponding C-glycosyl compounds, i.e. (4,6-di-O-acetyl-2,3-dideoxy-d-erythro-hex-2-enopyranosy)acetaldehyde (24,25) or the corresponding glycosylated methyl ketones 26, 27. A new route to C-3-branched glycals involves treatment of the above thioglycoside or the unsaturated vinyl glycosides with bis(benzoylmethyl)-mercury. © 1991.