Total synthesis of papulacandin D

Abstract

A total synthesis of (+)-papulacandin D which shows an antifungal activity is reported. The molecule is one of the members of C-arylglycoside isolated from Papularia spherosperma. The synthetic strategy bifurcates the molecule into two nearly equal subunits, the aryl glycoside 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. This highly convergent synthesis was accomplished in 31 steps overall from commercial starting materials.