Simple and catalyst-free synthesis of oxoindolin-3-yl phosphonates.

An efficient, simple, and catalyst-free synthesis of dialkyl or diaryl 3-(dicyanomethyl)-2-oxoindolin-3-ylphosphonates by the reaction of dialkyl or diaryl phosphites and oxoindolin-3-ylidenemalononitriles under solvent-free conditions is reported. The reaction of imino isatins with dialkyl or diaryl phosphites results in the formation of dialkyl or diaryl 2-oxo-3-(arylamino)indolin-3-ylphosphonates.