Disulfides and Boryl Sulfides Serve as both Initiators and Precatalysts in Radical Reductions of Halides by an N‐Heterocyclic Carbene⋅Borane

Diphenyl disulfide (PhSSPh), a typical boryl monosulfide (diiPr‐Imd‐BH₂SPh) and a typical boryl bis‐sulfide [diMe‐Imd‐BH(SPh)₂] all serve as both initiators and precatalysts in the reduction of alkyl and aryl halides by readily available 1,3‐dimethylimidazol‐2‐ylidene⋅borane (diMe‐Imd‐BH₃). The reactions are suggested to occur by a polarity reverse catalysis mechanism where in situ generated thiophenol is the active catalyst.