A New Complex of Palladium−Thiourea and Carbon Tetrabromide Catalyzed Carbonylative Annulation of <i>o</i>-Hydroxylarylacetylenes: Efficient New Synthetic Technology for the Synthesis of 2,3-Disubstituted Benzo[<i>b</i>]furans

Abstract

[reaction: see text] A highly effective cocatalysis system (PdI2-thiourea and CBr4) was developed for carbonylative cyclization of both electron-rich and electron-deficient o-hydroxylarylacetylenes to the corresponding methyl benzo[b]furan-3-carboxylates.