Epoxidation and Bis-hydroxylation of C-Phenyl-Δ(2,3)-glyco-pyranosides.

Epoxidation and cis-hydroxylation of C-phenyl-Δ(2,3)-glycopyranosides have been carried out with a view to developing C-aryl glycoside synthesis. Epoxidation of (2,3- dideoxy-d-erythro-hex-2-enopyranosyl)benzene and (6-O-tert-butyldimethylsilyl-2,3- dideoxy-d-erythro-hex-2-enopyranosyl)benzene gave predominantly the allo-adducts whatever the configuration at the anomeric center. Epoxidation of (4,6-di-O-tert-butyl-dimethylsilyl-2,3-dideoxy-d-erythro-hex-2-enopyranosyl)benzene gave the manno- and allo-adducts in a 89:11 and 40:60 ratios for the α- and β-anomers, respectively. Hydroxylation of α-C-phenyl-Δ(2,3)-glycopyranosides using OsO(4) afforded the manno-adduct only, whatever the substituents at positions 4 and 6, whereas hydroxylation of (2,3-dideoxy- β-d-erythro-hex-2-enopyranosyl)benzene and (4,6-di-O-tert-butyldimethylsilyl-2,3- dideoxy- β-d-erythro-hex-2-enopyranosyl)benzene gave the manno- and allo-adducts in 25:75 and 80:20 ratios, respectively.