Organocatalytic Glycosylation by Using Electron- Deficient Pyridinium Salts

A new organocatalytic glycosylation method based on electron-deficient pyridinium salts is reported. At ambient temperature and catalyst loadings as low as 1 mol%, 2-deoxyglycosides were formed from benzyl-and silyl-protected glycals and primary or secondary glycosyl acceptors, with excellent yields and anomeric selectivity. Mechanistic investigations point to alcohol-pyridinium conjugates (1,2-addition products) as key intermediates in the catalytic cycle.