Chemoselectivity control in the reaction of a dinuclear chloro-bridged cyclopalladated complex with potassium diphenylphosphide

Reactions of KPPh2 with the dimeric cyclopalladated complex {Pd(N∩C)(μ-Cl)}21 derived from N,N-dimethylbenzylamine were studied using different reagent ratios, temperature, reaction time, concentrations and solvents. Complex 3, the μ-Cl-μ-PPh2 analog of 1, was obtained in 76% yield in the one-hour reaction using the 1:1 ratio of dimer 1 and KPPh2 in THF at rt. ortho-(Diphenylphosphino)benzylamine 4 was synthesized in 58% yield by reacting complex 1 with 4.5 equiv. of KPPh2 in THF at rt. A possible mechanism of the aminophosphine formation is proposed on the basis of the experimental data including 31P{1H} NMR spectra of reaction mixtures.

Graphical abstractReaction of the dimeric cyclopalladated complex 1 with 1 equiv. of KPPh2 selectively provided the μ-Cl-μ-PPh2 analog 3 in 76% yield, while the use of 4.5 equiv. of KPPh2 furnished 58% of aminophosphine 4. A mechanism of the aminophosphine formation is proposed on the basis of the experimental data including 31P{1H} NMR spectra of reaction mixtures.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Chemoselectivity of the KPPh2 reaction with a CN-dimeric chloro-bridged cyclopalladated complex depends on the reagent ratio used. ► CN-Cyclopalladated complexes can be converted to the corresponding aminophosphines by reacting with 4.5 equiv. of KPPh2. ► The μ-Cl-μ-PPh2 and di-μ-PPh2 complexes appear to be intermediates of the aminophosphine formation from the correcponding di-μ-Cl cyclopalladated compounds and KPPh2.