I2-Induced Metal-Free C(sp2)–H Functionalization of Indoles via One-Pot and Two-Step Reaction with 1-(2-Hydroxyphenyl)-propargyl Alcohols: Access to 3-(Benzofuran-3-yl)-1H-indoles

Abstract

The I₂-catalyzed reaction of 1-(2-hydroxyphenyl)-propargyl alcohols with indoles and subsequent treatment with K₂CO₃ provided (benzofuran-3-yl)-1H-indoles in good to excellent yields with high regioselectivity. This one-pot and two-step strategy proved to be suitable for a wide range of substrates except for aliphatic alkynyl alcohols as well as the indoles bearing N-protected groups such as the Ts group possessing strong electron-withdrawing feature. The reaction procedure involved a cross-coupling and the construction of a benzofuran framework via 5-exo-dig cyclization.