Pyridine–hydrazone ligands in enantioselective palladium-catalyzed Suzuki–Miyaura cross-couplings

The geometries and coordination properties of modular pyridine–hydrazone N,N-ligands containing C2-symmetric trans-2,5-diphenylpyrrolidine and trans-2,5-diphenylpiperidine as the terminal dialkylamino units have been analyzed by X-ray diffraction analysis of [PdCl2(N,N)] complexes [(N,N)=pyridine hydrazone ligand]. In combination with Pd(OAc)2 as the precatalyst, these ligands provide high enantioselectivities (up to 95:5 er) in asymmetric Suzuki–Miyaura cross couplings of 2-methoxy-1-naphthyl bromides with 1-naphthyl and 2-tolyl boronic acids.

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