Selective Hydrodisulfuration of Alkenes with Dithiosulfonate

In this study, we have discovered the versatility of the dithiosulfonate reagent (ArSO₂-SSR) in transition metal catalyzed selective hydrodisulfuration of unactivated alkenes. The hydrodisulfuration displays a unique Markovnikov selectivity with a Salen-cobalt complex, while an anti-Markovnikov selectivity is observed when employing a nickel/bidentate N-donor ligand. Furthermore, precise control over nickel/ligand enables the successful achievement of remote site-selective hydrodisulfuration for both internal and terminal alkenes via a chain-walking process. In these processes, silanes are employed as a hydride source. Mechanistic insights into these innovative catalytic systems are also elucidated. Experimental findings suggest that Markovnikov hydrodisulfuration is likely to proceed through radical substitution on dithiosulfonate reagents, while nickel catalyzed anti-Markovnikov selectivity and remote site-selectivity likely occur via the radical addition of the reductively formed dithiosulfonate radical anion ([ArSO₂-SSR]⋅^-) to alkyl Ni^(II) species (alkyl-Ni^(II)L_nX) and subsequent reductive elimination on Ni^(III) intermediate (alkyl-Ni^(III)L_n(X)-SSR) as the key steps based on DFT calculation analysis.