Catalytic Enantioselective Total Syntheses of Bisorbicillinolide, Bisorbicillinol, and Bisorbibutenolide

A modified cinchona alkaloid catalyzed ketone cyanosilylation reaction is used as the stereochemistry-defining step in the total synthesis of sorbicillinol derivatives (a protected derivative is shown (PMB=para-methoxybenzyl)). These enantioselective total syntheses were accomplished in 10/11 steps and 12–19 % overall yields. Furthermore, the chemical conversion of bisorbicillinol into bisorbicillinolide provides insight into the biosynthesis of bisorbicillinolide.