Copper Catalyzed the Cross-Coupling Reaction of Arylthioaluminum Reagents with Alkynyl Bromides/Terminal Alkynes

A highly efficient and simple route for the synthesis of alkynyl sulfides has been developed by copper catalyzing the cross-coupling reaction of alkynyl halides/terminal alkynes with arylthioaluminum reagents. Various alkynyl sulfides can be obtained with 12-96% yields from the cross-coupling between alkynyl halides and arylthioaluminum reagents using 5 mol % Cu₂O/10 mol % TFP (tri(2-furanyl)phosphine) as the catalyst at 100 °C for 1 h. In the one-pot step-by-step method, various alkynyl sulfides can be obtained with 5-93% yields from the cross-coupling between terminal alkynes and arylthioaluminum reagents using 5 mol % Cu(OAc)₂/10 mol % DPPY (2-(diphenylphosphino)pyridine) as the catalyst at 100 °C for 3 h. The coupling reaction can be carried out smoothly regardless of the electron-donating or electron-withdrawing group on the aromatic ring of organic thioaluminum reagents or aryl terminal alkynes. In addition, the broad substrate scope and the typical maintenance of vigorous efficiency on the gram scale make this protocol a potentially practical method to synthesize alkynyl sulfides. On the basis of the experimental results, a possible catalytic cycle has been proposed.