Synthesis of the new chiral tridentate ligand bis(pyrid-2-ylethyl) menthylphosphine and its use in the palladium-catalyzed allylic alkylations

We describe the synthesis of a new asymmetric P,N,N′-tridentate ligand (bis(pyrid-2-ylethyl) menthylphosphine, BPEMP), containing two pyridyl rings and (1S,2R,5S)-menthylphosphino group. The ligand is obtained in five steps from natural abundant l-menthol. The coordination behavior of the ligand toward cationic (allylic)Pd(II) moiety and its first application in palladium-catalyzed asymmetric allylic alkylation are presented. Crystallographic and spectroscopic analyses reveal that (η³-allylic)Pd(BPEMP)]⁺ complex forms only one isomer in the solid state as well as in solution.