6-Phosphorylated Phenanthridines from 2-Isocyanobiphenyls via Radical C-P and C-C Bond Formation

A C-P bond and a C-C bond are formed in the synthesis of 6-phosphorylated phenanthridines starting with readily prepared 2-isocyanobiphenyls and commercially available P-radical precursors. The radical cascade reaction comprises addition of an oxidatively generated P-centered radical to the isonitrile functionality and subsequent homolytic aromatic substitution. Various 6-phosphorylated phenanthridines are formed in moderate to excellent yield. In contrast to the currently intensively investigated direct arene phosphorylation, the arene core is constructed with concomitant phosphorylation using this approach.