Total synthesis of papulacandin D

A total synthesis of the antifungal agent papulacandin D is reported. The molecule is representative of a large class of C-aryl glycosides that exhibit significant antifungal activity. The synthetic strategy bifurcates the molecule into two nearly equal subunits, the arylglycoside and 18-carbon fatty acid side chain. The key strategic transformations are (1) the palladium catalyzed, organosilanolate-based cross-coupling of a protected glucal silanol and (2) a catalytic enantioselective allylation of a dienal using allyltrichlorosilane. The synthesis was accomplished in 31 steps overall from commercial starting materials to afford over 50 mg of the natural product.