Regioselective ring-closing metathesis on terpenoid acrylates and acrylamides

Abstract

A series of acrylate esters was prepared by treatment of representative terpenoid aldehydes with allyl or vinyl magnesium bromide followed by reaction with acryloyl chloride. In all cases, ring-closing metathesis (RCM) resulted in regioselective formation of unsaturated lactones through metathesis of the acrylate and terminal olefins. After condensation of farnesal with a primary amine, a parallel series of reactions led to formation of the corresponding lactam.