Development of Transition-metal Catalysts and Their Applications to Asymmetric Catalysis

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Development of environmentally-benign processes is most important and challenging task in the 21^<st> century. In our efforts directed towards this task, we have succeeded in development of highly stereoselective catalytic asymmetric syntheses.1.Highly enantio- and diastereoselective hydrogenation of α-amino-β-keto estersRecently, we have demonstrated that α-amino-β-keto esters have been directly hydrogenated in an anti-selective manner with ruthenium-BINAP catalyst to provide β-hydroxy-α-amino acid esters. From further investigation on this hydrogenation, we have found that iridium-axially chiral phosphine also hydrogenates α-amino-β-keto esters to afford efficiently the β-hydroxy-α-amino acid esters.2.Catalytic asymmetric synthesis using chiral diaminophosphine oxidesTransition metal-catalyzed reaction using secondary phosphine oxides or their equivalent have attracted attention in these past several years due to the air and moisture stability of pentavalent phosphine oxides. We succeeded in development of P-chiragenic phosphine oxides based on a chiral diamine framework : aspartic acid-derived P-chirogenic DIAPHOXs. These pentavalent phosphorus compounds, the preligands, reacted with BSA to provide the trivalent diaminophosphite species, which functioned as the actual ligands. With use of the Pd-DIAPHOX catalyst system, asymmetric allylic alkylation, asymmetric allylic amination, and enantioselective construction of quaternary carbons have been achieved.