Electrochemical reduction of 5-benzylidene thiazolidine-2,4-diones: a greener approach to the preparation of glitazone APIs

A transition-metal free methodology for the chemoselective reduction of benzylidene thiazolidine-2,4-diones and similar heterocycles is described, allowing the preparation of a broad scope of the corresponding reduced derivatives in up to 90% yield. The protocol has a simple and safe experimental setup, in which water was employed as the hydrogen source. To further demonstrate the synthetic utility of this transformation, the antidiabetic API Pioglitazone was prepared in 81% yield. To the best of our knowledge, this is the first hydride and transition-metal free protocol for the synthesis of Pioglitazone, highlighting its potential utility as a greener alternative in both academic and industrial synthesis.