Ni-catalyzed reductive cross-couplings of diaryl disulfides with aryl bromides for biaryl synthesis through C-S bond cleavage

Abstract

In previous reports, the cross-couplings of diaryl disulfides with aryl halides in the presence of transition metal catalyst (e.g., Ni, Cu) and metal mediator (e.g., Mg, Zn) usually led to the corresponding aryl sulfides via old S-S bond cleavage and new C-S bond formation. In the present study, we found that the reductive cross-couplings of diaryl disulfides with aryl bromides proceeded via unusual C-S bond cleavage in the presence of nickel catalyst, magnesium, and lithium chloride in THF at room temperature, leading to a variety of biaryls in modest to good yields. In addition, the reaction could be scaled-up with ease. Mechanistic studies showed that the reaction possibly proceeds via the in situ production of arylmagnesium compound as reaction intermediate via LiCl-facilitated Mg insertion into aryl bromide. Most importantly, the combinatory use of Ni(II) catalyst and Mg mediator is the key for the unusual cleavage of the C-S bond in diaryl disulfide to form the corresponding arylnickel(II) species which serves as another important intermediate of the present desulfurated cross-coupling reaction.