Exclusive Markovnikov Synthesis of Tertiary Phosphine Sulfides from Secondary Phosphine Oxides, S ₈ , and Alkenes

A novel one-pot synthesis of valuable tertiary phosphine sulfides from secondary phosphine oxides, elemental sulfur (S 8 ), and alkenes has been developed, featuring exclusive Markovnikov selectivity. This method offers significant advantages in the one-pot construction of three new C–P(═S) chemical bonds. It exhibits a broad substrate scope, accommodating mono-, di-, tri-, and even tetrasubstituted alkenes, and can be readily scaled up to a gram scale. Mechanistic investigations revealed two key steps: (1) an unexpected disproportionation process that cleaves the robust P═O bonds of dialkylphosphine oxides and (2) the Markovnikov hydrophosphination of alkenes with an in situ generated dialkylphosphine intermediate.