Efficient Synthetic Approach to Substituted Benzo[<i>b</i>]furans and Benzo[<i>b</i>]thiophenes by Iodine‐Promoted Cyclization of Enaminones

Abstract

An efficient synthetic approach to the substituted benzo[ b ]furan and benzo[ b ]thiophene scaffolds by iodine‐mediated cyclization of the corresponding enaminones is described. This protocol was applied to a large series of these latter precursors to afford the respective benzoheterocycles substituted at the C‐2 position by a carbonyl group functionality. A study of the factors that control this process reveals that the reactivity depends on the presence of electron‐donor groups in the aryl ring of the aryloxycarbonylic and arylthiocarbonylic moieties.