Supporting-electrolyte-free electrochemical [2 + 2 + 1] annulation of benzo[d]isothiazole 1,1-dioxides, N-arylglycines and paraformaldehyde

The H-bond promoted electrochemical [2 + 2 + 1] annulation of benzo[d]isothiazole 1,1-dioxides, N-arylglycines and paraformaldehyde for the synthesis of various benzo[d]imidazo[1,5-b]isothiazole 5,5-dioxide derivatives under redox mediator, catalyst and electrolyte-free conditions was developed.