Nickel-Catalyzed Suzuki Cross Couplings with Unprotected Allylic Alcohols Enabled by Bidentate N-Heterocyclic Carbene (NHC)/Phosphine Ligands

Cross couplings between simple allylic alcohols and aryl and vinyl boronic acids are efficiently catalyzed by nickel(0) catalysts and bidentate N-heterocyclic carbene/phosphine ligands. The bidentate nature of the ligand is shown to extend catalyst lifetime and enable high yields of the corresponding cross-coupling products. X-ray crystallography confirms the bidentate nature of the ligand scaffold. Multistep cross coupling-alkene/alkyne insertions reactions are also conducted and the bidentate nature of the substrate makes the pendant phosphine of the ligand unnecessary.