1, 6-Dihydro-3 (2H)-pyridinones. IV. Synthesis of (±)-Tabersonine and (±)-Cleavamine via a Common Intermediate, Ethyl 3-Ethyl-3-hydroxy-1, 2, 3, 6-tetrahydropyridine-1-carboxylate

A formal synthesis of (±)-tabersonine (1) and a total synthesis of (±)-cleavamine (2) have been achieved via a common intermediate (6) derived from ethyl 1, 6-dihydro-3 (2H)-pyridinone-1-carboxylate (5a). The successful cyclization of the carboxylic acid (20) to the dioxocleavamine (4) is also discussed.