Solvent‐Controlled and Cobalt‐Catalyzed Addition of H‐Phosphine Oxides to α ‐CF ₃ Styrenes

A cobalt‐catalyzed switchable reaction of α ‐trifluoromethyl styrenes with diarylphosphine oxides is developed. Simply by changing the solvent, this protocol delivers two different fluorine‐containing organophosphorus products, that is phosphinoyl defluorination products in acetonitrile, and hydrophosphinylation products in methanol. The reaction proceeds under mild conditions with broad functional group tolerance and good yields. Mechanistic studies support a carbanion pathway rather than a radical process. Gram‐scale synthesis further demonstrates its practicality. This work offers a controllable, efficient route to CP bonds from readily available α ‐trifluoromethyl alkenes, expanding the synthetic toolkit for fluorinated organophosphorus compounds.