TEMPO-Promoted Domino Heck-Suzuki Arylation: Diastereoselective Cis-Diarylation of Glycals and Pseudoglycals

A palladium-catalyzed regio- and diastereoselective diarylation of glycals and pseudoglycals, which is a kind of Heck-Suzuki arylation, is described. A wide range of arylboronic acids reacted under these conditions smoothly. Selectivity was C1-C2(alpha,alpha) in the case of glycals but C2-C3(beta,beta) for pseudoglycals. Quantum chemical analysis has been carried out to establish the reaction mechanism, which may involve Pd(II)/Pd(O). TEMPO plays a key role in the formation of diaryl glycoside due to its radical nature.