A Simple Route to Benzofurans

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.