Synthesis of substituted 2-cyclopenten-1-ones from oxodithioesters via a domino process

Freshly prepared sulfines of delta-oxodithioesters underwent chemoselective addition of methyllithium to the electron poor sulfur atom of the thiocarb onyl moiety. Subsequent ring closure was effected by intramolecular additio n of the carbanion, generated in situ, to the delta-carbonyl function leadi ng to 2-cyclopenten-1-ones. While most described intramolecular procedures involve a base-catalysed cyclisation, our method is induced by an addition reaction. It is a new efficient synthesis of substituted 2-cyclopenten-1-on es via a domino process. (C) 1999 Elsevier Science Ltd. Ail rights reserved .