Visible-Light-Driven Decarboxylative S -Allylation via In Situ Generated Palladium(II) Sulfide Charge-Transfer Complexes: A Sustainable Approach to Allyl Aryl Sulfides

The conventional Pd(0)-catalyzed (2e^- process) has emerged as a powerful approach to catalyze different decarboxylative reactions of γ-methylidene-δ-valerolactones under mild conditions. We found that a combination of triphenylphosphine and palladium(II) sulfides in situ generated from Pd(PPh₃)₄ and arylthiophenol can catalyze allylation of arylthiophenol by decarboxylative coupling of γ-methylidene-δ-valerolactones through the formation of a charge transfer complex under 427 nm irradiation by blue LEDs, giving a variety of allyl aryl sulfides in good to excellent yields. Mechanistic studies indicate that a radical pathway can account for the decarboxylative C(sp³)-S coupling of thiophenols with γ-methylidene-δ-valerolactones, which did not give the corresponding products in the presence of Pd(PPh₃)₄.