Flexible Strategy for Syntheses of Spirooxindoles using Palladium-Catalyzed Carbosilylation and Sakurai-Type Cyclization

The intramolecular carbosilylation of N-[2-(1,3-butenyl)aryl]carbamoyl chloride has been investigated. The reaction with hexamethyldisilane proceeds smoothly in the presence of a catalytic amount of [Pd(eta(3)-allyl)Cl](2) to give oxindoles with an allylsilane functional group in good yield. The subsequent subjection of the products to a Sakurai-type reaction provides more advanced tricyclic spirooxindoles by controlling the stereochemistry of three contiguous stereogenic centers.