A Simple Route to Benzofurans

Abstract

Recently, we have demonstrated that anilines could be selectively ortho-substituted with relative ease and in high yield via the intramolecular rearrangement of ylids generated from azasulfonium salts.^3,4 These azasulfonium salts could be derived from either the reaction of sulfides with N-chloroanilines³ or from the reaction of anilines with chlorosulfonium chlorides.⁴ Utilizing a variation of this technology we have recently demonstrated that phenols can be selectively ortho-alkylated⁵ or ortho-formylated.⁶ These processes are illustrated by the conversion of 1 into 2 in 73% yield and the subsequent reduction of 2 to 3 in 95% yield, and by the transformation of 4 into 6 via 5 in 35% overall yield.