Room Temperature Ni‐Catalyzed Ullmann Reaction of (Hetero)aryl / Vinyl Chlorides Enabled by Silylchloride‐Activated Mn Powders

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A room temperature Ni‐catalyzed Mn‐mediated homocoupling of (hetero)aryl and vinyl chlorides using Mn powders pre‐activated by trimethylsilylchloride (TMSCl) in DMA is reported. Large steric effects were observed while electronic influences from aryl chlorides proved to be rather small. High regioselectivity could be achieved between ortho ‐Cl and para ‐Cl/Br of aryl halides benefiting from the large steric effects. A double‐face role of TMSCl, i. e. activation of Mn powders but deactivation of nickel catalyst, was observed although TMSCl‐activated Mn powders appeared to be the privileged metallic reductant. Applications of the protocol have been demonstrated in a multigram synthesis of Daclatasvir.