Synthesis of Substituted Cyclopentenes from the Baylis-Hillman Adducts via Ring-Closing Metathesis Reaction

Abstract

Recently, we reported the synthesis of 2,5-dihydrofuran and 2,5-dihydropyrrole systems by using the well-known ring-closing metathesis (RCM) reaction from the slightly modified Baylis-Hillman adducts. 1 As a continuing effort we intended to synthesize the cyclopentene skeleton as shown in Scheme 1. Cyclopentene ring is a carbon analog of 2,5dihydrofuran and 2,5-dihydropyrrole systems and we thought we could construct the cyclopentene ring by using the similar strategy, namely the combination of BaylisHillman chemistry and RCM reaction. Substituted cyclopentenes have been synthesized in a variety of ways 2-4 including the ring-closing metathesis (RCM) reaction 2,4 and have been used as useful synthetic