Synthesis and Characterization of Air‐Stable Palladium(II) and Copper(I) Ph‐Garphos Complexes and their Applications to Asymmetric Catalysis

Abstract Air‐stable palladium(II) and copper(I) complexes containing the 4,4′,6,6′‐tetramethoxybiphenyl‐2,2′‐diyl)bis(diphenylphosphine) ligands, ( R )‐Ph‐Garphos (( R )‐ L1 ) and (( S )‐Ph‐Garphos (( S )‐ L1 ), were synthesized and characterized by 1 H‐, 13 C‐, and 31 P{ 1 H} NMR spectroscopy and elemental analyses. The PdCl 2 (( R )‐Ph‐Garphos) (( R )‐ 1 ) and PdCl 2 (( S )‐Ph‐Garphos) (( S )‐ 1 ) complexes were assessed for the Suzuki‐Miyaura cross‐coupling of aryl halides with phenylboronic acid under ambient conditions, or naphthyl substrates under reflux. X‐ray crystal structures of the copper complexes revealed that [Cu(( R )‐Ph‐Garphos)I] (( R )‐ 2 ) crystallized as a three‐coordinate monomer in the orthorhombic space group P 2 1 2 1 2 1 whereas [Cu(( S )‐Ph‐Garphos)I] (( S )‐ 2 ) crystallized as a tetrahedral (μ‐I) dimer in the same crystal system. The synthesis of the analogous [Cu(( R )‐Ph‐Garphos)OAc] (( R )‐ 3 ) is also described. Complexes ( R )‐ 2 and ( R )‐ 3 were evaluated for the asymmetric hydrosilylation of ketones wherein enantioselectivities of up to 83 % ee were achieved.