Ruthenium-catalyzed ROM-RCM of Cyclopentene-yne. Concise Synthesis of a Pyrrolizidine Derivative

Abstract

ROM-RCM (Ring-Opening Metathesis and Ring-Closing Metathesis) of cyclopentene-yne having an ester moiety was demonstrated using first- and second-generation Grubbs' catalysts. When the reaction of cycloalkene-yne was carried out in the presence of 5 mol % of a ruthenium carbene complex under ethylene atmosphere at room temperature, ROM-RCM proceeded smoothly to give a pyrrolidine derivative in good yield, which could be converted to a pyrrolizidine derivative.