Synthesis and Characterisation of 1-[9-(H, Me3Si, Me3Ge, Me3Sn)9-Fluorenyl]-3,7,10-trimethylgermatranes. The Crystal Structure Analysis of 1-(9-Fluorenyl)-3,7,10-trimethylgermatrane
摘要:
The title compounds, viz. C13H8(R)Ge . (OCHMeCH2)(3)N (1: R = H, 2: R = Me3Si; 3: R = Me3Ge) were prepared as mixtures of diastereomers by the reaction of N(CH(2)CHMeOSnAlk(3))(3) (7: Alk = Et; 8: Alk = Bu) with C13H8(R)GeBr3 (4: R=H, 5: R=Me3Si; 6: R=Me3Ge), respectively. The synthesis of C13H8(Me3Sn)Ge (OCHMeCH2)(3)N (13) by the reaction of germatrane (1) with Me3SnNMe2 is reported. Identity and structures were established by elemental analyses,H-1 and C-13 NMR spectroscopy and mass spectrometry. The crystal structure of 1 was determined by X-ray diffraction methods.
Mechanistic Studies of the Zirconium−Triisopropanolamine-Catalyzed Enantioselective Addition of Azide to Cyclohexene Oxide
摘要:
The mechanism of the enantioselective ring-opening of cyclohexene oxide by Me3SiN3, catalyzed by zirconium complexes of the C-3-symmetric ligand (+)-(S,S,S)-triisopropanolamine, has been investigated. Measurements of molecular weights of precatalyst species show that complexes are formed with average trimeric aggregation. Kinetics measurements reveal the overall process to be approximately half order in total zirconium, epoxide, and Me3SiN3 components. The reaction also shows a strong nonlinear relationship between enantiomeric excess of product azido ether vs the incorporation of (R,S,S)-triisopropanolamine ligand in the catalyst mixture. On the basis of these and other results, a preequilibrium interconversion of dimeric and tetrameric zirconium-triisopropanolamine species is proposed to occur rapidly with respect to the rate of epoxide ring-opening, with the dimeric form being the active catalyst. The reaction is accelerated by silyl ethers or by small amounts of water or alcohol, whereas larger amounts of protic additives inhibit the reaction. Enantioselectivity is eroded at catalyst concentrations less than 1 mole-percent and at high concentrations of cyclohexene oxide. Both enantioselectivity and rate are influenced to a small extent by the nature of the silyl azide employed for the first catalytic turnover, suggesting that a silyl fragment becomes irreversibly incorporated in the catalyst structure. It is proposed that catalytic activity requires the cooperative action of two zirconium centers for the binding and delivery of azide to epoxide.
Metal-organic frameworks containing nitrogen-donor ligands for efficient catalytic organic transformations
申请人:The University of Chicago
公开号:US10647733B2
公开(公告)日:2020-05-12
Metal-organic framework (MOFs) compositions based on nitrogen donor-based organic bridging ligands, including ligands based on 1,3-diketimine (NacNac), bipyridines and salicylaldimine, were synthesized and then post-synthetically metalated with metal precursors, such as complexes of first row transition metals. Metal complexes of the organic bridging ligands could also be directly incorporated into the MOFs. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
Provide that a useful catalyst for homogeneous hydrogenation, particularly a catalyst for homogeneous asymmetric hydrogenation for hydrogenation, particularly asymmetric hydrogenation, which is obtainable with comparative ease and is excellent in economically and workability, and a process for producing a hydrogenated compound of an unsaturated compound, particularly an optically active compound using said catalyst with a high yield and optical purity.
Use of electrospray ionization mass spectrometry to characterize chiral reactive intermediates in a titanium alkoxide mediated sulfoxidation reaction
作者:Marcella Bonchio、Giulia Licini、Giorgio Modena、Stefano Moro、Olga Bortolini、Piero Traldi、William A. Nugent
DOI:10.1039/a701227f
日期:——
The ESIMS technique, combined with
1
H NMR evidence, provides
a precise inventory of the catalytic Ti
IV
precursors and the
characterization of the reactive peroxometal complex involved in
enantioselective sulfoxidation employing the
Ti
IV
–homochiral trialkanolamine–alkylhydroperoxide
system.
ESIMS 技术与 1 H NMR 证据相结合,提供了催化 Ti IV 前体的精确清单,并描述了采用 Ti IV - 同手性三烷醇胺 - 烷基过氧化氢体系进行对映选择性硫氧化作用时所涉及的活性过氧金属复合物的特征。
New Titanatranes: Characterization and Styrene Polymerization Behavior
作者:Youngjo Kim、Yonggyu Han、Jeong-Wook Hwang、Myong Woon Kim、Youngkyu Do
DOI:10.1021/om0109197
日期:2002.3.1
they exist in the monomeric form in the solid state and the Ti atom adopts essentially an η5 bonding posture with the Cp‘ ring and a tetradentate bonding mode with the trialkanolatoamine ligand via a transannular interaction from the bridgehead N atom to Ti. All compounds show very high catalytic activity for the syndiospecificpolymerization of styrene in the presence of modified methylaluminoxane
在三乙胺的存在下,通过各种三烷醇胺与(C 5 Me 4 R)TiCl 3(Cp'= C 5 Me 4 R)的反应,制备了含有环戊二烯基配体的新的钛烷烃。X射线分析表明,它们在单体形式存在于固态和钛原子基本上采用一个η 5与CP”环接合姿势并与来自含有桥头氮的trialkanolatoamine配体经由一个跨环相互作用四齿键合方式钛原子。在改性甲基铝氧烷(MMAO)助催化剂的存在下,所有化合物均表现出很高的催化苯乙烯间间聚合反应的催化活性。
Dimolybdenum Bis((<i>S</i>,<i>S</i>,<i>S</i>)-triisopropanolaminate(3−)): A Blue Compound with an Unusual Mo−Mo Triple Bond
作者:Malcolm H. Chisholm、Ann M. Macintosh、John C. Huffman、Dedong Wu、Ernest R. Davidson、Robin J. H. Clark、Steven Firth
DOI:10.1021/ic991352d
日期:2000.8.1
Mo2(OtBu)6 and Mo2(NMe2)6 each react with (S,S,S)-triisopropanolamine (2 equiv) in benzene to yield dimolybdenum bis((S,S,S)-isopropanolaminate(3-)), Mo2[(OC-(S)-HMeCH2)3N]2 (M identical to M), as a blue crystalline solid. Cell parameters at -160 degrees C: a = 17.389(6) A, b = 10.843(3) A, c = 10.463(3) A, beta = 125.28(1) degrees, Z = 2 in space group C2. The molecular structure involves an Mo2 unit