Unique Reactivity of the 1,4‐Bis(silyloxy)‐1,3‐cyclopentadiene Moiety: Application to the Synthesis of 7‐Norbornanone Derivatives

Abstract

We describe a method for the synthesis of various 2‐silyloxy‐2‐norbornen‐7‐ones that exploits the specific reactivity of the 1,4‐bis(silyloxy)‐1,3‐cyclopentadiene framework, which is generated under silylating reaction conditions from a 2,2‐disubstituted‐1,3‐cyclopentanedione bearing the picolinoyloxy group at the 2' position of its C‐2 side chain. Our reaction system generates a carbocation via the release of the acyloxy group, forms a 4,5‐cis‐fused ring skeleton via the intramolecular attack at the resulting carbocation by a silyloxy‐substituted carbon in the 1,4‐bis(silyloxy)‐1,3‐cyclopentadiene moiety, and induces the skeletal rearrangement of the bicyclic core. This novel transformation of a 1,3‐cyclopentanedione moiety can be developed for the synthesis of other bicyclic frameworks fused to cyclopentenones.