2-pyridones from cyanoacetamides and enecarbonyl compounds: application to the synthesis of nothapodytine B.

The condensation of an enone or enal with cyanoacetamide derivatives and t-BuOK furnishes either 3-cyano-2-pyridones or 3-unsubstituted-2-pyridones, depending on whether the reaction is carried out in the presence or in the absence of O(2). In the first case, in situ oxidation of Michael-type intermediates takes place; in the second case, the products result from "decyanidative aromatization" of such intermediates. A one-step synthesis of 3-alkyl-2-pyridones has been devised on the basis of decyanative union of an enone/enal and a 2-alkylcyanoacetamide. The new reaction forms the centerpiece of an unusually concise synthesis of nothapodytine B (mappicine ketone).