Synthesis of Dibenzophosphole Oxides from Dibenzothiophene Dioxides and Phenylphosphine by Two Successive SNAr Reactions

One‐pot treatment of dibenzothiophene dioxides with phenylphosphine and KOH in DMSO at ambient temperature provides the corresponding dibenzophosphole oxides after oxidative workup. Substitution of the endocyclic SO 2 unit with PPh could proceed via an intermolecular S N Ar reaction of the dioxides with potassium phenylphosphide followed by another S N Ar reaction in an intramolecular fashion. Various dibenzophospholes have been synthesized from readily available dibenzothiophene dioxides and were investigated from a photophysical viewpoint.