Renmao Liu

Stereoselective C-glycosylation reactions with arylzinc reagents.

A general, transition-metal-free, highly stereoselective cross-coupling reaction between glycosyl bromides and various arylzinc reagents leading to β-arylated glycosides is reported. The stereoselectivity of the reaction is explained by invoking anchimeric assistance via a bicyclic intermediate. Stereochemical probes confirm the participation of the 2-pivaloyloxy group. Finally, this new method was applied to a short and efficient stereoselective synthesis of Dapagliflozin and Canagliflozin.

Carboxylate directed cross-coupling reactions in the synthesis of trisubstituted benzoic acids.

The carboxylate anion has been used as a directing group to effect selective ortho-substituted derivatives 3 (>99:1 selectivity 50-80% yield). The solvent, base, and equivalents of base are the determining factors for the success of this reaction. The directing effect can be reversed by the appropriate use of phosphine ligands to prepare the para-substituted 4 selectively (ca. 12:1 selectivity).