An exclusive approach to 3,4-disubstituted cyclopentenes and alkylidene cyclopentenes via the palladium catalyzed ring opening of azabicyclic olefins with aryl halides

A simple and efficient method for the stereoselective ring opening of bicyclic hydrazines with various aryl halides under palladium catalysis has been elaborated. The reactions afforded trans-3,4-disubstituted cyclopentenes or alkylidene cyclopentenes in good to excellent yields. By taking advantage of multiple points of functionalization in the synthesized trans-3-phenyl-4-hydrazino-cyclopentene, we have synthesized the antidepressant Cypenamine (trans-2-phenylcyclopentylamine).