Lewis acid catalysed cyclisation and halogen exchange reactions of 1,1′-biphenyl-2-yl isocyanide dihalides
Abstract
1,1′-Biphenyl-2-yl isocyanide dichloride and dibromide undergo unprecedented intramolecular Friedel–Crafts type cyclisation reactions catalysed by various Lewis acids affording useful synthetic methods for otherwise difficult to access 6-chloro- and 6-bromo-phenanthridines; nucleophilic displacement reactions of the latter and halogen exchange reactions of 1,1′-biphenyl-2-yl isocyanide dichloride and dibromide are also described.