Ligand-assisted nickel-catalysed sp3–sp3 homocoupling of unactivated alkyl bromides and its application to the active template synthesis of rotaxanes

An efficient, mild and operationally simple Ni-catalysed sp3-carbon-to-sp3-carbon homocoupling of unactivated alkyl bromides has been developed and utilised in the active metal template synthesis of an alkyl chain axle 2rotaxane. The key to the transformation is the use of tridentate nitrogen-donor-atom (terpy or pybox derived) ligands which inhibit competing β-hydride elimination of alkyl-Ni intermediates.