A two-step sequence is described for conversion of cyclic and acyclic ketone enolates into a- methylenevalerolactones. The first step involves Michael addition to ethyl a- ((phenylsulfony1) methyl) acrylate 1 with concomitant elimination of PhS02 and formation of unsaturated keto esters 2-7. In the next sequence chemoselective ketone reduction is usually followed by spontaneous lactonization of acidification. Contrary to the five-and six- ...
