A General and Scalable Synthesis of Polysubstituted Indoles

A consecutive 2-step synthesis of N-unprotected polysubstituted indoles bearing an electron-withdrawing group at the C-3 position from readily available nitroarenes is reported. The protocol is based on the [3,3]-sigmatropic rearrangement of N-oxyenamines generated by the DABCO-catalyzed reaction of N-arylhydroxylamines and conjugated terminal alkynes, and delivers indoles endowed with a wide array of substitution patterns and topologies.