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.