Microwave-Assisted Synthesis of Phenanthridines by Radical Insertion/Cyclization of Biphenyl Isocyanides

A rapid microwave-assisted approach for the synthesis of phenanthridine derivatives from the radical insertion/cyclization reaction of biphenyl isocyanides with a C(sp3)–H bond adjacent to a heteroatom has been developed. The protocol achieves wide substrate scope and good to excellent yields. The kinetic isotope effect (KIE) studies, radical inhibition studies, and Hammett plot analysis clearly disclose that the current reaction supports a radical mechanism.