Practical Synthesis of (±)-Chlorovulone II

Abstract

We describe a total synthesis of (±)-chlorovulone II that is 10 steps shorter than the best alternative currently available (nine vs 19 steps). The key event of the synthesis is an aldol addition of the enolate of ethyl acetate into 4-cyclopentene-1,3-dione, a substance that has received little attention as an educt for prostanoid synthesis and for which little is known about carbonyl 1,2-addition with enolates. In addition, we provide chemical and stereochemical details of a route to a key intermediate toward the title compound that involves a carbonyl−ene reaction and a radical addition to an aldehyde carbonyl.