Substitution of Cl Atom in (2-Chloromethylallyl)palladium Complexes with Soft and Hard Nucleophiles

Article abstract of DOI:10.1246/bcsj.71.877

[Pd{η³-CH₂C(CH₂Cl)CH ₂}(μ-SPh)]₂ is spontaneously transformed, in MeCN, into [Pd{η³-CH₂C(CH₂SPh)-CH ₂}(Cl)]₂, which has a novel thioether-bridged dimeric structure. This transformation is suggested to proceed by an attack of the thiolate anion at the methylene carbon bearing a Cl substituent of an ionic intermediate, [Pd{η³-(CH₂C(CH₂Cl)CH ₂}(MeCN)₂]⁺. [Pd{η³-CH₂C(CR₂Cl)CH ₂}(μ-SPh)]₂ (R = H, Me) reacts with PPh₃ to give [Pd{η³-CH₂C(CH₂SPh)CR ₂}(Cl)(PPh₃)]. This transformation proceeds via an attack of the thiolate anion at the terminal allyl carbon of an ionic intermediate, [Pd{η³-CH₂C(CH₂Cl)CH₂}(PPh ₃)₂]⁺, to give 2-phenylthiomethylallyl chloride, which undergoes an oxidative addition to the resulting Pd(0) complexes. [Pd{η³-CH₂C(CR₂Cl)CH ₂}(Cl)(PPh₃)] (R = H, Me) reacts with Bu₃SnCH=CH₂ to give [Pd{η³CH₂C(CH₂CH=CH₂)CR ₂}(Cl)(PPh₃)] through a reductive elimination-oxidative addition sequence, starting from an intermediate, [Pd{η³-CH₂C(CR₂Cl)CH ₂}(CH=CH₂)(PPh₃)].