Convergent and Efficient Synthesis of Spiro

Article abstract of DOI:10.1021/jo00175a011

A synthesis is presented of spiro<7-methoxybenzofuran-3(2H),4'-piperidines>, tricyclic analogues containing the A, N, and O rings of codeine.Two successive 1,4-additions into a pyridine residue, an intermolecular aryllithium addition followed by an intramolecular ester enolate ring closure, establish the spiro system.Reduction and finally α-methylene lactam rearrangment provide the necessary functionalization for further elaboration and C-ring closure.