Rongalite as a mild reductant for solvent-assisted dechlorination of 3,3-dichlorooxindoles to 3-chloro-2-oxindoles and 2-oxindoles

Abstract

A mild, metal-free, and solvent-controlled reductive dechlorination method has been developed for synthesizing 3-chloro-2-oxindoles, and 2-oxindoles from 3,3-dichlorooxindoles. In this process, Rongalite serves as a mild reducing agent, achieving monodechlorination in polar protic, and complete dehalogenation in polar aprotic solvents, leading to the formation of 3-chloro-2-oxindoles, and oxindoles, respectively. This methodology features several advantages, including the use of inexpensive reagents, mild reaction conditions, simple operational procedures, high yields, and short reaction times.