Pd-catalyzed direct functionalization of glycals with cycloalkenones: application to the synthesis of chiral phenanthrenones.

A palladium-catalyzed direct C-H functionalization of glycals with cycloalkenones is described and a series of C-2 functionalized glycals were synthesized efficiently with cyclic enones. The direct C-H functionalization of glycals with Pd(II) and subsequent insertion of cyclic enones via β-hydride elimination is the key to the synthesis of 2C-branched glycals. The synthetic utility of this methodology for chiral phenanthrenones has also been demonstrated by coupling the synthesized 2C-branched glycals with arynes via 4+2 cycloaddition followed by concomitant pyran ring opening.