Copper-catalyzed coupling reaction of unactivated secondary alkyl iodides with alkyl Grignard reagents in the presence of 1,3-butadiene as an effective additive.

Cu-catalyzed cross-coupling of unactivated secondary alkyl iodides with alkyl Grignard reagents in the presence of 1,3-butadiene as a ligand precursor was developed. The use of 1,3-butadiene resulted in improved yields of alkyl-alkyl products with improved selectivities.