In this study, malononitrile was selected as a nucleophile with two acidic protons to be directed toward a double Mannich reaction3–6. In the interactions of nitriles with late transition metal salts, malononitrile can bind to two metal atoms7. For example, for the 5th-period elements, the two metal centers should be around 7.5 Å from each side of the malononitrile unit (Fig. 2A). In order to achieve a dinuclear reaction in one asymmetric reaction sphere while retaining the same geometry, a novel phosphoiminoBINOL ligand was designed, as shown in Fig. 2B. The phosphoimino moiety is designed to capture soft metals such as Pd, Rh, Au, Ag, and Cu, and the soft dinuclear complex binds strongly to malononitrile (or an anion of malononitrile generated during the reaction). The phenol functions in the ligand contribute by stabilizing the intermediate through hydrogen bonding. If the phenols incorporate a hard metal such as Li, Mg, or Zn, the resulting metal phenoxide acts as a Brønsted base, enhancing the catalytic activity. The hard Lewis acidity of the metal phenoxide is also characteristic.Figure 2Design of Malononitrile Container. (A) Geometry of malononitrile bound to two metals, (B) Design of the multifunctional dinuclear phosphoiminoBINOL-metal complex for binding malononitrile. (C) Preparation of phosphoiminoBINOL ligands.