Synthesis of symmetrical triarylphosphines from aryl fluorides and red phosphorus: scope and limitations

The reaction of aryl fluorides with phosphide anion, generated in situ from the reduction of red phosphorus by lithium metal in liquid ammonia, gave symmetrical triarylphosphines in fair to good yields. Phosphonodiamide, sulfonamide, 2-oxazolyl, and nitrile groups were stable to the reaction conditions, while nitro and bromo substituents were not. para-Substituted aryl fluorides gave higher yields than meta-substituted aryl fluorides, and ortho-substituted aryl fluorides failed to react.