Development of New Lewis Acid Catalysts based on Late-Transition Metal Complexes

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In order to develop a new class of Lewis acid catalysts, complexes of late-transition metals have been investigated including chiral skeleton on the binding oragnic parts. The new complexes have been characterized by NMR and X-ray analysis. The catalysts have also designed to have some profiles, such as water tolerable and recyclable.We have developed new type of ligands including chiral oxazoline-pyridine derivatives, bis(oxazolinyl)pyridines, bis(oxazolinyl)phenyl, and bis(oxazolinyl)xantenes, which were derived from optically active beta-aminoalcohols. We have determined structures of several rhodium, ruthenium, platinum, and palladium complexes with oxazoline skeletons by X-ray analysis. Espetially, Phebox-Rh complexes exhibited catalytic activity as Lewis acids to promote Diels-Alder reaction, hetero-Diesl-Alder reaction, and aldol reactions giving higher enantioselectivities. The catalyst shows the activity in aqueous media.