Discovery of Zinc Thiolates as the Missing Link in Ni‐Catalyzed Reductive C(sp) 2 –S Coupling †

Comprehensive Summary Nickel‐catalyzed reductive coupling of organic halides with sulfur electrophiles has emerged as a robust strategy for accessing a diverse array of valuable sulfur‐containing molecules. However, its mechanism remains incompletely elucidated, primarily due to the lack of studies on characterization of multiple nickel intermediates ( e.g ., Ni(I)/Ni(II)/Ni(III)), as well as the mechanistic roles of reductive metal additives. Herein, we identify the rapid oxidative addition of zinc to the S–S bond of disulfides as a pivotal step that enables subsequent transmetallation with arylnickel(II) adducts. Furthermore, we discovered that the zinc serves as additional two critical roles: it not only reduces the Ni(II)‐precatalyst to active Ni(0) specie, but also mediates the reduction of sulfur electrophiles ( e.g ., N ‐thiophthalimides or thiosulfonates) to the corresponding disulfides. We also report the first example of a base‐free, nickel‐catalyzed Negishi‐type thiolation of (hetero)aryl halides using bench‐stable zinc dithiolates, thereby furnishing a versatile alternative to established methodologies for the synthesis of structurally diverse C(sp 2 )‐rich sulfides.