Development of Highly Selective Asymmetric Reaction Systems Utilizing Transition Metal Complexes

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1. Asymmetric hydrogenation of dehydrooligopeptides: For the asymmetric hydrogenation of Y- phe-(S or R)-AA-OH, novel achiral diphosphine DPP-AE having amino moiety was developed, and Rh - DPP-AE catalyst afforded high stereoselectivities(84 96%d.e.) irrespective of the amino protecting groups(Ac or Z) where electrostatic interaction between DPP-AE and substrate was expected. By detailed studies, it was concluded that the electrostatic interaction between ligand and substrate enabled a multi-points recognition by the complex to cause highly efficient 1,4-asymmetric induction. The selectivity was strongly dependent on the solvent polarity and methanol afforded best results among alcohols examined. Introduction of electron-donating group(o-me and p-Me) to DPP-AE enhanced the substrate-specificity. Specific dependency of the selectivity on the temperature was observed in these Rh-DPP-AE systems. 2. Asymmetric alkylation of cyclic allylic compounds: Pd-chiral diphosphinite(POP) systems wer … More e proved to be more effective for the enantiotopos-selective alkylation of cyclic allylic compounds than diphosphine systems. POP was modified in order to alter the electronic and steric factors of the ligand. Introducton of methoxly group to the m-position of the phenyl substituent of POP or unsymmetrization of the two phosphinoxy groups was effective to raise the enantio-selectivity. The reaction was also dependent on the structure of the enolate anion and 50%e.e. was obtained in the reaction using dimethyl acetylaminomalonate anion in methanol. 3. Asymmetric nucleophilic addition to imine compounds: The conversion of Co(III)- amino acidato complex to xhiral Co(III)-imino acidato complex was examined, and the conditions of dehydrogenation and <beta>-elimination were established corresponding to the structure of the amino acidato complexes. The crystal structure of thr Co-imino acidata complex was determined. The complex adopted a <LAMBDA>_2 configuration with a planar imino acidato chelate. Reduction of the imino acidato complex by NaBH4 addorded an optically active amino acidato complex in a high yield. Less