Modular Synthesis of Chiral beta-Aminophosphine P,N-Ligands and Their Applications in Asymmetric Catalysis.

摘要

A series of chiral beta-aminophosphine ligands bearing different carbon backbones and electronically differentiated diarylphosphino groups were prepared using a modular approach. These P,N-ligands were found to induce a modest level of enantioselectivities in the Pd-catalyzed asymmetric decarboxylative allylation reaction. Thiourea-phosphine bifunctional catalysts derived from the chiral beta-aminophosphine building blocks were prepared and applied to the asymmetric Morita-Baylis-Hillman (MBH) reaction of methyl acrylate and 4-nitrobenzaldehyde. The electronically unmodified diarylphosphino-thiourea was found to be optimal for achieving high activity and enantioselectivity in this particular MBH reaction. We also reported the synthesis of a P-chiral C2-symmetric bisphosphine ligand. However, the utility of this Trost-type ligand remains to be explored in the future.