Pd-catalyzed coupling reactions of anhydro-aldose tosylhydrazones with aryl bromides to produce substituted exo-glycals.

Palladium-catalyzed cross-couplings of O-peracylated and O-permethylated 2,6-anhydro-aldose tosylhydrazones with aryl halides were studied under thermic conditions in the presence of LiOtBu and phosphine ligands. The reactions gave the corresponding aryl substituted exo-glycals as mixtures of diastereomers in 11-75% yields. The transformations represent a new access to these types of glycomimetic compounds. The double bond of some aryl substituted exo-glycals was saturated to give good yields of benzylic C-glycosyl derivatives.