Stereoselective trimethylsilylation of α- and β-galactopyranoses

Abstract Trimethylsilylation of the anomeric hydroxyl groups of tetra- O -benzyl and tetra- O -acetyl galactopyranoses was investigated. Stereoselective formation of β-trimethylsilyl glycoside (β-TMS glycoside) of benzyl protected compound was achieved using N -trimethylsilyl diethylamine. In the course of the investigation of the selective synthesis of TMS galactosides using TMS-imidazole, we observed the formation of an intermediate, which was converted predominantly into α-TMS glycoside after silica gel column chromatography. A reaction of acetylated compound using TMS-trifluoromethanesulfonate–2,6-lutindine selectively yielded α-TMS glycoside.