Cross-Electrophile Coupling of Vinyl Halides with Alkyl Halides

An improved method for the reductive coupling of aryl and vinyl bromides with alkyl halides that gave high yields for a variety of substrates at room temperature with a low (2.5 to 0.5 mol %) catalyst loading is presented. Under the optimized conditions, difficult substrates, such as unhindered alkenyl bromides, can be coupled to give the desired olefins with minimal diene formation and good stereoretention. These improved conditions also worked well for aryl bromides. For example, a gram‐scale reaction was demonstrated with 0.5 mol % catalyst loading, whereas reactions at 10 mol % catalyst loading completed in as little as 20 minutes. Finally, a low‐cost single‐component pre‐catalyst, (bpy)NiI2 (bpy=2,2′‐bipyridine) that is both air‐ and moisture‐stable over a period of months was introduced. Win/Win! An improved method for the coupling of aryl and vinyl bromides with alkyl halides that gave high yields for a variety of substrates while lowering the catalyst loading and temperature of the reactions is presented. Alkenyl bromides gave the desired olefins with near complete stereoretention. Reactions can be run with as low as 0.5 mol % catalyst loading or reactions with a higher loading finish in as little as 20 minutes (see scheme).