Investigation into the nickel catalyzed cross-coupling continued and increased the scope of the reaction after these first examples were shown and the research interest grew. Miyaura and Inada reported in 2000 that a cheaper nickel catalyst could be utilized for the cross-coupling, using triphenylphosphine (PPh3) instead of the more expensive ligands previously used. However, the nickel-catalyzed cross-coupling still required high catalyst loadings (3-10%), required excess ligand (1-5 equivalents) and remained sensitive to air and moisture. Advancements by Han and co-workers have tried to address that problem by developing a method using low amounts of nickel catalyst (<1 mol%) and no additional equivalents of ligand.