| Co-Investigator(Kenkyū-buntansha) |
SHINMYOZU Teruo Kyushu Univ., Fac. of Sci., Assot. Prof., 理学部, 助教授 (90037292)
KATSUKI Tsutomu Kyushu Univ. Fac. of Sci., Professor, 理学部, 教授 (40037271)
MATSUMOTO Naohide Kyushu Univ., Fac. of Sci., Assistant, 理学部, 助手 (80145284)
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| Research Abstract |
Stereoselectivities of six-coordinate complexes of 4- (l-menthyloxy) -1-phenyl-1, 3-butanedione (H (l-moba) ) and 4- (l-menthyloxy) -1-p-tolly-1, 3-butanedione (H (l-moba-Me) ) have been examined for various metal ions (Co, Cr, Mn, IIIA, IIIB, Ianthanoid). In particular the complexes of IIIA and IIIB ions were studied by means of 400 MHz H-NMR and CD spectroscopies. All the complexes showed a stereoselectivity to afford the fac-OMEGA from predominantly because of the operation of a non-covalent interaction in the from of a left-handed three-bladed propeller, comprising three interligand l-menthyl/aryl contact. The interligand contact became efficient when the central metal ion was significantly large (r>l.OA^^ﾟ).
Such sterically controlled lanthanoid complexes Ln (l-moba-Me)_3 were used as Lewis acid catalysts for enantioselective reductions of ketones. Acetophenone was converted into (S) -alcohol (e e % 84) whereas butane-2-one and octane-2-one were converted into (R) -alchols.
Stereose
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lectivities of tetrahedral or pseudo-tetrahedral Co (II), Cu- (II), and Zn (II) complexes of N- (l-menthyl) salicylaldimine (H (sal-ment) ) and N- (R) -alpha-methylbenzylsalicylaldimine (H (sal-Rmb) ) have been studied by single-crystal X-ray method, CD spectroscopy, and molecular mechnics Calculations. The preferred configuration was DELTA for tetrahedral [M (sal-ment)_2] (M=Co, Cu, Zn), OMEGA for tetrahedral [M (sal-Rmb)_2] (M=Co, Zn), and DELTA for pseudo-tetrahedral [Cu (sal-Rmb)_2]. The X-ray structural analyses for [M (sal-Rmb)_2] clearly demonstrated the operation of non-covalent interactions between the chiral N-substituent and the adjacent ring. The Cotton effect induced at the azomethine pi-pi^* transition was well correlated with the absolute configration about the metal center.
Stereoselectivities of planar metal (II) complexes (M=Cu, Pb, Pt)) of N-substituted ethylenediamines, N- { (R) -alpha-methylbenzyl} ethylenediamine (R-mben), N- { (S) -alpha-methylbenzyl} ethylenediamine (S-mben), and N- (l-menthyl) -ethylenediamine (mten), have been examined by electronic absorption and CD spectroscopies and interpreted based on a regional rule (hexadecadalrule). The preferred conformation with respect to the ethylene chain were delta for the mten and B-mben complexes and lambda for the S-mben complexes. Less
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