＜正＞ Over the last decade, C2-symmetric chiral oxazoline metal complexes have been recognized as an effective c...
FU, Bin DU, Da-Ming WANG, Jian-Bo(Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education , College of Chemistry and Molecular Engineering, Peking University, Beijing 100871)
The chiral o-hydroxyphenyloxazoline ligands were synthesized and their metal complexes with Cu, Ni and Ti were prepared. The crystal structure of complex 2a formed by ligand 1a with Cu (molar ratio 2:1) was determined by single-crystal X-ray diffraction analysis, and it belongs to monoclinic, space group P21 with a = 11.679(2), b = 17.681(4), c = 12.838(3) ? b = 106.50(3), C26H32N2O4Cu, Mr = 500.08, V = 2541.8(9) 3, Z = 4, F(000) = 1052, Dc = 1.307 g/cm3, m = 0.892 mm-1, the final R = 0.0448 and wR = 0.0930 (I > 2s(I)). In the asymmetric unit of complex 2a, there exist two types of molecules which are self-associated by intermolecular O…Cu interactions, and 揹imeric complex?is thus formed. The distances of the Cu and O atoms of a pair of intermolecular coordinated molecules are 2.828 ?for Cu(1)…O(21) and 2.776 ?for Cu(2)…O(13), respectively. The coordination N and O atoms and the central Cu are slightly deviated from coplanarity.
＜正＞ The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand leading...
CHEN, Xiao ZHANG, Yong-Xin DU, Da-Ming HUA, Wen-Ting( Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education , College of Chemistry and Molecular Engineering , Peking University , Beijing 100871)
N (1 Phenyl 2 hydroxyethyl) 2,3 naphthylenedicarboximide(1a) was obtained by the reaction of 2,3 naphthylenedicarbonitrile with R phenylglycinol. 2,3 Naphthylenedicarboxylic acid, when reacts with thionyl chloride, gives 2,3 naphthalenedicarboxylic acid cyclic anhydride rather than the corresponding 2,3 naphthalenedicarboxylic acid dichloride. The former, when reacts with S leucinol, gives corresponding dicarboximide(1b). The crystal structure of compound 1a was determined by an X ray single crystal diffraction analysis. Compound 1a: C 40 H 30 N 2O 6, F W=634 66, orthorhombic, space group P 2(1)2(1)2(1), a =1 15556(5) nm, b =3 16552(12) nm, c =0 85984(3) nm; α= 90°, β=90°, γ=90°, V =3 1452(11) nm 3, Z=4, \{F(000)=\}1328, D c=1 340 g/cm 3, μ =0 091 mm -1 . Reflections collected/unique, 28053/4068( R int =0 0411); Final R indices : R 1=0 0337, wR 2=0 0687; Largest diff. peak and hole, 248 and \{-222\} e·nm -3 .
WANG Zhan yueDU Da mingWU DiHUA Wen tingJIN Xiang lin
Over the last decade, C2-symmetric chiral oxazoline metal complexes have been recognized as an effective classof chiral catalyst in a variety of transition metal catalyzed asymmetric reactions. [1] High catalytic activities and enantiomeric excesses have been obtained using C2-symmetric chiral ligands in conjunction with suitable transition metal ion, for example, the hydrosilylation of ketone, allylic alkylation, Michael addition, Diels-Alder cycloaddition, and cyclopropanation. Thus, the design and synthesis of new chiral oxazoline ligands have inspired many scientists to work with great efforts.……
Bidentate and tetradentate ligands containing the oxazoline unit have been successful in a range of asymmetric transformations.[1~3] Chiral tridentate ligands may form a deeper chiral concave pocket around the metal center, and have been less extensively used in asymmetric catalysis than their bidentate or tetradentate analogues. Nishiyama's tridentate "pybox"ligand, in which a pyridine ring links two chiral oxazoline moieties, has been successfully used in various asymmetric reactions.……
Catalytic asymmetric synthesis of tertiary cyanohydrins by the addition of cyanide to a wide range of ketones has important synthetic utility, since the resulting optically active cyanohydrins are important intermediates for the synthesis of a variety of valuable classes of chiral compounds. The application of oxazoline in asymmetric cyanosilylation has seldom reported in comparation with other reactions.[1] Recently, polymer-supported pyridine-bis(oxazoline) ytterbium complex was reported to catalyze cyanosilylation of benzaldehyde.……
