Catalytic C(sp²)–C(sp³) Cross-Electrophile Coupling in the Pt^II–NaI–С₂Н₃I–СН₃I–Acetone System

A new catalytic system for reductive С(sp²)–C(sp³) cross-electrophile coupling was designed: Pt^II iodide complexes in an acetone solution of NaI catalyze the coupling of methyl iodide with vinyl iodide to form propylene. Simultaneously, a small amount of 1,3-butadiene, the product of C(sp²)–C(sp²) coupling, is released. The total yield of the products with respect to the reacted vinyl iodide is almost quantitative. In a large excess of CH₃I, the C₂H₃I consumption is described by the pseudo-first-order kinetics. The cross-coupling occurs as the following sequence of steps: oxidative addition of CH₃I to Pt^II iodide complexes to form a methyl Pt^IV complex → reduction of the methyl Pt^IV complex with I^– to form the corresponding Pt^II derivative → oxidative addition of C₂H₃I to the Pt^II derivative → reductive elimination of organyl ligands from the intermediate methyl vinyl Pt^IV complex.