Application of the Silyloxy Cope Rearrangement of Chiral Aldol Products Towards a Synthesis of (+)-Lasiol

A stereoselective total synthesis of the natural product (+)-lasiol (1) has been achieved. The key step of our synthesis is a silyloxy-Cope rearrangement of the chiral, silylated aldol product 2 which proceeds selectively through the chair-like transition state with the silyloxy group in the pseudoaxial and the carboximide group in the pseudoequatorial position. The two methyl-substituted stereogenic centers of the natural product are generated with ds > 97:3. The rearrangement product 4 is converted to the natural product via a Wittig olefination reaction and an oxidative cleavage of a double bond, respectively.