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 pseudoequato rial position. The two methyl-substituted stereogenic centers of the n atural product are generated with ds > 97:3. The rearrangement product 4 is converted to the natural product via a Wittig olefination reacti on and an oxidative cleavage of a double bond, respectively.