Nickel-catalyzed coupling of aryl bromides in the presence of alkyllithium reagents

An easy approach towards the synthesis of compounds using coupling reactions of bromide compounds was demonstrated. A comparison of different alkyllithium reagents was made by examining the coupling of bromobenzene (1a). The molar ratio of bromobenzene to catalyst was 138:1 using [NiCl 2(dppp)] and bromobenzene, Bpy was added to the reaction solution as a ligand. Alkyllithium was added at half molar equivalents to that of phenyl bromide groups with the intention of generating an equimolar ratio of lithiated benzene anions to unreacted phenyl bromide groups. It was observed that decreasing the amount of [NiCl2(dppp)] from 25 to 12 mg, while maintaining the ratio to bpy, did not have a substantial effect on the yield of biphenyl formed. The one-pot synthetic technique demonstrate the use of alkyllithium reagents with a catalytic amount of nickel to syntheisze coupled aryl compounds.