NCS-Mediated Direct C(sp 3 )-H Oxygenation of 2-Methylindoles Using Water as the Oxygen Source.

In continuation of our research interest in the green oxidation of indoles, we further explore the direct oxidation of 2-methylindoles to 2-formyl indoles promoted by NCS and associated with H 2 O as the oxygen source. This methodology was demonstrated to be a robust protocol consisting of chlorination, S N 2', and oxidation processes, and presents a reasonably broad substrate scope and excellent functional group tolerance, thus enabling the preparation of high added-value versatile building blocks susceptible to further functionalization.