Microwave-assisted synthesis of 3-substituted indoles via intramolecular arene-alkene coupling of o-iodoanilino enamines

A generally applicable and high-yielding protocol for the synthesis of 3-substituted indole derivatives is described. Key features include microwave-assisted intramolecular arene-alkene coupling of o-iodoanilino enamines, and expedient synthesis of o-iodoanilino enamine substrates employing N,O-acetal TMS ethers, which could be conveniently derived from the corresponding amides. Our unique procedure seems quite efficient and provides an easy access to a variety of 3-substituted indoles as privileged structure for a wide range of biological targets.