Development of Asymmetric Catalysis of Synthetic Reactions

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The purpose of this work is to develop efficient asymmetric catalysis of some C-C bond forming reactions. A summary of the research results is as follow: (1) Catalytic Stereocontrol in Asymmetric Aldol reactions : Using Eu(III)-complexes as a catalyst, high levels of distereocontrol have been achieved in the aldol reactions of chiral alpha-amino aldehydes with ketene silyl acetals Furthermore, the catalytic aldol technology has successfully been applied to asymmetric synthesis of the key intermiediates of carbapenem antibiotics and renin inhibitors. (2) Asymmetric catalysis of Carbonyl-Ene Reactions : The chiral titanium complex derived from optically active binaphthol was found to serve as an efficient asymmetric catalyst for glyoxylate-ene reaction to provide a practical access to alpha-hydroxy esters in high enantiomeric excess. Interestingly, the phenomenon of "asymmetric amplification" was observed and its mechanistic origin was elucidated. (3) Asymmetric Catalysis of Diels-Alder Type Reactions : The above-mentioned chiral titanium comples was found to serve as an asymmetric catalyst for hetero D.-A. reaction with the glyoxylate and D.-A.reactions with methacrolein and quinones. (4) Asymmetric Catalysis of Allylmetal/Aldehyde Addition Reactions : The abovementioned chiral Ti-complex was also found to be an efficient asymmetric catalyst for the addition reactions of allylic silanes and stannanes to the glyoxylate. (5) Asymmetric Catalysis of Claisen Rearrangement : A palladium (II) complex was found to show an efficient and diastereoselective catalysis of the Claisen rearrangement via an ether exchange process. However, the development of an asymmetric catalyst has been still unsuccessful. Further work is in progress.