Reaction of o-phenylenediamine with 2,3-dichloromaleic anhydride: synthesis of N-substituted maleimide derivatives and 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one. X-ray structures of 2,3-dichloro-N-o-C6H4(NH2)maleimide and N, N′-o-C6H4-bis(2,3-dichloromaleimide) |