Abstract:
Chlorination of 2-aryl-1-hydroxyindole-5,6-dicarbonitriles with N-chlorosuccinimide affords previously unknown 3,3-dichloro-3H-indole 1-oxides instead of the expected 1-hydroxy- 3-chloroindoles. The latter can be prepared in good yields by treatment of the above 3,3-dichloro-3H-indole 1-oxides with piperidine in ethanol.