MMTr as an efficient anomeric S-protecting group for the synthesis of glycosyl thiols

The 4-monomethoxytrityl (MMTr) group was introduced in high yields to anomeric sulfhydryl functions using commercially available MMTrCl. Significantly, it is stable to a variety of reaction conditions, including acids and bases, and is removable under very mild acidic conditions, which are compatible with the presence of a number of other acid-labile hydroxyl protecting groups. The successful preparation of seven glycosyl thiols indicates that MMTr has potential application for the synthesis of complex 1-thiosugars.