Reflux of equimolecular amounts 2-aminobenzylamine and isatins in acetic acid produced indolo [3, 2-c] quinolin-6-ones in good yields. A proposed mechanism involving initial formation of a spiro compound is given. This isolable intermediate subsequently rearranges via a sequential isocyanate ring opening and a cyclisation process to a urea derivative which finally cyclized to the indolo [3, 2-c] quinolin-6-ones. The urea derivative could be ...