| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Optically active quadridentate 18-membered crown thioether, Binaph_2Me_4 [18] S_4, incorporating two C_2-axially dissymmetric 1,1'-binaphthyl groups, and quadridentate 17-membered BinaphMe_6 [17] S_4 and tridentate 13-membered BinaphMe_4 [13] S_3, incorporating one 1,1'-binaphthy1 group, were enantioselectively synthesized and their structures were elucidated unequivocally by an X-ray analysis. The Rh (I,III), Ru (II), Pd (II), Pt (II), and Ni (II) complexes with these chiral Binaph_2Me_4 [18] S_4, BinaphMe_6 [17] S_4 and BinaphMe_4 [13] S_3 ligands were prepared. Binaph_2Me_4 [18] S_4 was fully preorganized for a planar coordination to metal ions due to the inherent twist about pivotal bonds of 1,1'-binaphthyl moieties to afford doubly helical Sq.planar and Oh complexes of D_2 symmetry. BinaphMe_6 [17] S_4 gave singly and doubly helical Oh complexes with up-up-up-down and up-down-up-down conformations where up and down indicate the direction of lone pair orbitals on the S atom with respect to the equatorial 4S plane, and their conformations were influenced by central metals and axial ligands. Asymmetric hydrosilylation reaction of ketones and asymmetric Grignard cross-coupling reaction catalyzed by these helical Rh (I,III) and Ni (II) complexes were examined to reveal the ability of these sulfur helicates as asymmetric catalysts and the capability of the helical cavity discriminating te chirality, which was affected by the number of 1,1'-binaphthyl moieties and ring members.
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