Photocatalytic Synthesis of 6-Phosphorylated Phenanthridines from 2-Isocyanobiphenyls via Radical C−P and C−C Bond Formation

A mild, efficient, photocatalytic synthesis of 6-phosphorylated phenanthridines via tandem radical addition/cyclization/aromatization of 2-isocyanobiphenyls with diarylphosphine oxides is reported. The method features operational simplicity in metal-free conditions, using low-cost Rose Bengal as a catalyst and sustainable air as a terminal oxidant at room temperature and providing the desired products in moderate to good yields.