Development of Routes for the Stereoselective Preparation of β-Aryl--glycosides via -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 -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 -1 aryl enones with Pd-C/H provides the β-isomer of 2-deoxy-aryl--glycosides in excellent yield. The 1 aryl enones were also used as precursors for the synthesis of 2-hydroxy-β-aryl--glycosides. Regioselective -2 halogenations and vinylations of -1 aryl enones were achieved in excellent yields.