Abstract The quinolinetriones TMCH, PCH, MCH and phenalene trione (PT) do not react with aryl isocyanates to Schiff bases 5a, but react by ring contraction to yield the spiro- imidazolidines 2 ad, 3 ae, 4 ab and 5 ac bd. However, reaction of ninhydrine with aryl isocyanates gives the 1: 2 adductes 1 ae. Benzal aniline reacts with TMCH, PCH. and PT to yield known phenoxazine derivatives 2c, 11. In contrast, PCH or MCH react with ...
