TOTAL SYNTHESIS OF DL-PENTALENOLACTONE

The synthesis of dl-pentalenolactone has been achieved in a stereospecific way. The key features of the synthesis were (1) a Diels-Alder route to 5-acylcyclohexenones via selective deacylation of a 4,5-diacylcyclohexenone (see 30 → 31), (2) a new route to a-methylene-5-lactones via the Brederick reagent (see 4 → 64 → 65 → 66 → 66a → 5), and (3) the stereospecific introduction of an epoxymethylenelactone via an epoxyhemiacetal (see 5 → 6). © 1979, American Chemical Society. All rights reserved.