Utilization of Ethyl 2-((Phenylsulfonyl)methyl)acrylate for the Synthesis of α-Methylenevalerolactones

Article abstract of DOI:10.1021/jo00311a014

A two-step sequence is described for conversion of cyclic and acyclic ketone enolates into α-methylenevalerolactones.The first step involves Michael addition to ethyl α-((phenylsulfonyl)methyl)acrylate 1 with concomitant elimination of PhSO2 and formation of unsaturated keto esters 2-7.In the next sequence chemoselective ketone reduction is usually followed by spontaneous lactonization on acidification.Contrary to the five- and six-membered ring systems, the cis-fused isomer predominates in the seven- and eight-membered ring compounds 12 and 13.Spiro α-methylenevalerolactones 17a,b are as well obtainable by a short sequence of steps from 2-oxocyclohexanecarboxylate and 1.