New Pd(II) and Pt(II)-diaminophosphine complexes bearing cyclohexyl or isopropyl moiety: use of Pd(II) complexes as precatalyst in Mizoroki--Heck and Suzuki--Miyaura cross-coupling reactions

Abstract

Two new diaminophosphine ligands, $N$,$N$'-bis(dicyclohexylphosphino)-2-(aminomethyl)aniline (\textbf{1}) and $N$,$N$'-bis(diisopropylphosphino)-2-(aminomethyl)aniline (\textbf{2}) were synthesized by the reaction of 2-(aminomethyl)aniline with two equivalents of Cy$_{2}$PCl or (iPr)$_{2}$PCl, respectively. The reactions of \textbf{1 }and \textbf{2} with MCl$_{2}$(cod) (M = Pd, Pt; cod = 1,5-cyclooctadiene) yield complexes [\textit{cis}-Pd(L$_{2}$\textbf{P}NHC$_{6}$H$_{4}$CH$_{2}$NH\textbf{P}L$_{2})$Cl$_{2}$] (L = Cy \textbf{3}, iPr \textbf{4}) and [\textit{cis}-Pt(L$_{2}$\textbf{P}NHC$_{6}$H$_{4}$CH$_{2}$NH\textbf{P}L$_{2})$Cl$_{2}$] (L = Cy \textbf{5}, iPr \textbf{6}), respectively. The catalytic activity of the palladium complexes was investigated in the Suzuki--Miyaura cross-coupling reaction in the presence of Cs$_{2}$CO$_{3}$ as a base. The palladium complexes were also found to be highly active catalysts in the Mizoroki--Heck reaction.