Development of Routes for the Stereoselective Preparation of β-Aryl-C-glycosides via C-1 Aryl Enones

A wide range of enones derived from D-glucal, D-galactal, L-rhamnal, D-rhamnal, and L-arabinal underwent Heck-coupling with various arylboronic acids bearing electron-donating and -withdrawing groups in the presence of palladium acetate and 1,10-phenanthroline. These reactions provided synthetically useful C-1 aryl enones in good yields. Many sensitive functional groups as well as protecting groups present in arylboronic acids and enones, respectively, remained intact under optimized conditions. The stereoselective hydrogenation of C-1 aryl enones with Pd-C/H-2 provides the beta-isomer of 2-deoxy-aryl-C-glycosides in excellent yield. The C-1 aryl enones were also used as precursors for the synthesis of 2-hydroxy-beta-aryl-C-glycosides. Regioselective C-2 halogenations and vinylations of C-1 aryl enones were achieved in excellent yields.