Divergent Electrochemical Tandem Addition/Cyclization of Isothiocyanates with Allylamines: Access to Thiazolidin-2-imines and Benzothiazoles.

A KI-mediated electrochemical tandem addition/cyclization of isothiocyanates with allylamines affords thiazolidin-2-imines and benzothiazole-type products in an undivided cell. The protocol provides 53 products, including drug-derived substrates. Product-distribution studies and DFT calculations reveal substrate-controlled competition between 5-exo-trig alkene cyclization and arene C-S annulation: phenyl systems favor alkene cyclization, whereas strongly activated or π-extended arenes favor arene annulation. Mechanistic experiments support an iodide-enabled radical pathway.