Reactivity of dimeric cyclopalladated complexes with an (sp3)C–Pd bond toward KPPh2

Abstract

Reactions of KPPh2 with dimeric C,N, C,P and C,S cyclopalladated complexes (CPCs) 1a−g containing an (sp3)C–Pd bond were investigated. The CPCs used in the study were obtained from D-camphor O-methyloxime (a), l-fenchone O-methyloxime (b), 4,4-dimethyl-2-phenyl-2-oxazoline (c), 8-methylquinoline (d), trimesitylphosphine (e), tri(O-tolyl)phosphine (f) and 2,6-dimethylthioanisole (g). The dichloro-bridged CPCs 1a,b,d,f,g and the diacetato-bridged analog μ-OAc-1d reacted with 4.5 equiv. of KPPh2 at room temperature in THF to give either phosphines 2a,b or phosphine oxides 8d,f,g in 20–51% yield. Complexes 1a,b,d reacted with 1 equiv. of KPPh2 to produce the corresponding μ-chloro-μ-diphenylphosphido-CPCs 3a,b,d in 33–56% yield. In the reaction of CPC 1c with 4.5 equiv. of KPPh2, complex 4c with two PPh2 bridging ligands was isolated in 36% yield. Structures of phosphines 2a,b, phosphine oxides 8a,d,f,g as well as complexes 3a,b,d and 4c were confirmed by 1H, 13C{1H} and 31P{1H} NMR spectroscopy.