NiCl2/Hdipm-Catalyzed 2-OH-Selective Alkylation of Glycoside trans-Diols.

A strategy for site-selective controllable alkylation of α-glycosides bearing an equatorial trans-2,3-diol utilizing NiCl2/Hdipm or SnCl2/DIPEA catalysis is reported. Studies on various catalytic systems have revealed that only the NiCl2/Hdipm-catalyzed alkylation could achieve excellent 2-O selectivity. This method was further applied to the efficient one-pot synthesis of both 2-OH and 3-OH glycosyl acceptors. Via the one-pot method, 2-O-methyl-empagliflozin (a potential anti-heart failure drug) was synthesized from empagliflozin with a total 76% yield.