Deformylative Oxidative Rearrangement of 2-Formylindoles Enabled by NCS as a Metal-Free Edit

Abstract

Deformylative functionalization is a promising but difficult route to value-added molecules. Continuing our work on metal-free indole oxidation, we report a mild, solvent-controlled deformylative oxidative rearrangement of 2-formylindoles to 2-oxindoles and 3-chlorooxindoles in moderate to high yields. Using only NCS as the oxidant and trace H₂O as a green H/O source, this cascade method offers broad substrate scope, excellent functional group tolerance, operational simplicity, scalability, and versatile access to high-value building blocks.