A facile synthesis of dibenzopyrroloazepinones as tetracyclic allocolchicinoids-an unusual 1,2-phenyl shift

A facile synthesis of dibenzopyrroloazepinones via an electrophilic cyclisation of a biphenyl-acyliminium ion is described; an unusual 1,2-phenyl shift occurs when the C-1' carbon is the more nucleophilic than the C-2' carbon.