Acetonitrile-Mediated Synthesis of 2,4-Dichloroquinoline from 2-Ethynyl­aniline and 2,4-Dichloroquinazoline from Anthranilonitrile

2,4-Dichloroquinolines and 2,4-dichloroquinazolines were synthesized from 2-ethynylanilines and anthranilonitriles, respectively, using diphosgene in acetonitrile and heating at 130 °C or 150 °C for 12 hours. This reaction was applied to the synthesis of 4,6dichloropyrazolo[3,4-d]pyrimidine (dichloro-9H-isopurine). The postulated mechanism is also described.