Regiospecific Bromination—Cyclization of Spirocyclic Cyclohexanones and Its Application to the Synthesis of (.+-.)-Laurencial.

Abstract Stereospecific bromination-cyclization of spirocyclic cyclohexanones having an isopropylidenedioxy group was found to proceed under thermodynamically controlled conditions, which was applied to the first synthesis of (±)-laurencial and its epimer.