Catalyst-Free One-Pot Tandem Reduction of Oxo and Ene/Yne Functionalities by Hydrazine: Synthesis of Substituted Oxindoles from Isatins

Abstract

An unprecedented hydrazine-mediated tandem reduction of oxo and N-ene/yne functionalities of substituted isatins is reported to access various oxindoles. The reaction is performed by treating N-(2-alkenyl)/propargylisatins with hydrazine hydrate under catalyst-free refluxing conditions. The reduction proceeds efficiently without the aid of any catalyst at ambient pressure.