A new cinnoline synthesis. Part VI. 4-Mercaptocinnolines

Abstract

4-Mercaptocinnolines are obtained in good yield from the 4-hydroxy-compounds by reaction with phosphorus pentasulphide in pyridine. The corresponding amines are prepared readily from the mercapto-compounds by treatment with ammonia or primary amines. The amination reaction fails with nitro-4-mercaptocinnolines. The reaction of the 4-mercapto-derivatives with hydrazine, methylating agents, and Raney nickel is described. Treatment of 6-chloro-4-mercaptocinnoline with chlorine in acetic acid gave a good yield of 4,6-dichlorocinnoline and not the expected 4-sulphonyl chloride.