With this fascinating container for malononitrile (L1-Pd2) in hand, the optimum catalyst for the conventional single Mannich reaction was examined before we attempted the challenge of the double Mannich reaction (Table 1)8–23.Table 1Development of dinuclear phosphoiminoBINOL-metal catalyst for Mannich reaction using malononitrile. EntryLigandAdditiveYield (%)a2a/3aee of 2a (%)1 L1 —9983/1782 L1 LiOAc8684/16103 L1 NaOAc9972/28264 L1 Mg(OAc)29157/43745 L1 Ca(OAc)29474/26306 L1 Zn(OAc)29360/40687 L1 ZnCl28892/878 L1 Zn(OTf)26693/7189 L2 Zn(OAc)24696/41110 L3 Zn(OAc)27285/153711 L4 Zn(OAc)27868/327712 L5 Zn(OAc)27378/22613b) L6 Zn(OAc)27590/101014b) L7 Zn(OAc)26592/8rac15c) L1 Zn(OAc)27073/2791a)Conversion yield (see details for the determination in SI). b)10 mol % of Pd(OAc)2 were used. c)5 mol % of PhosphoiminoBINOL, 10 mol % of Pd(OAc)2, and 5 mol % of Zn(OAc)2 were used. Imine 1a was slowly added over 4 h.