Cyclometallated Palladium Diphosphane Compounds Derived from the Chiral Ligand (S)-PhCH(Me)NMe2. Michael Addition Reactions to the Vinylidene Double Bond

Treatment of (S)‐PhCH(Me)NMe2 (1) with palladium(II) acetate in toluene gave the dinuclear cyclometallated complex [Pd{(S)‐C6H4CH(Me)NMe2‐C2,N}(μ‐OAc)]2 (2), inwhich the ligand is bonded to the palladium atom through the nitrogen phenyl carbon atoms. The reaction of 2 with aqueous sodium chloride gave the chloro‐bridged complex 3. The reaction of 3 with (R,R)‐DIOP [(4R,5R)‐4,5‐bis(diphenylphosphanylmethyl)‐2,2‐dimethyl‐1,3‐dioxolane], in a complex/phosphane 1:1 molar ratio, gave [{Pd[(S)‐C6H4CH(Me)NMe2‐C2,N]Cl}2(μ‐(R,R)‐DIOP)] (4). The reaction of 3 with (Ph2P)2C=CH2 (vdpp) in a 1:2 molar ratio in the presence of NH4PF6 or NaClO4 afforded [Pd{(S)‐C6H4CH(Me)NMe2‐C2,N}{(Ph2P)2C=CH2‐P,P′}][Y] [Y = PF6– (5); Y = ClO4– (6), respectively]. The treatment of 5 with acetylacetone in the presence of anhydrous sodium carbonate or with methanol afforded the addition products, [Pd{(S)‐C6H4CH(Me)NMe2‐C2,N}{(Ph2P)2CHCH2R‐P,P′}][PF6] [R = CH(COMe)2 (7); R = OMe (8), respectively], in good yield. The treatment of 6 with methyl acetoacetate and anhydrous sodium carbonate afforded the addition derivative [Pd{(S)C6H4CH(Me)NMe2C2,N}{(Ph2P)2CHCH2CH‐(COMe)(COOMe)‐P,P′}][ClO4] (9). The NMR spectra of the addition products showed that some of the resonances were duplicated due to the existence of optical isomers. The X‐ray crystal structure of complexes 2, 5, and 7 were determined by single‐crystal X‐ray diffraction analysis. Chiral palladacycles were prepared from ligand 1. Those that involve the functionalized diphosphane vdpp may give complexes that bear more than one stereogenic center, which originate after the Michael addition to the vinylidene double bond.