离子液体促进四氟硼酸铜催化芳醛和乙酸酐合成1,1-二乙酸酯

在室温条件下, 离子液体1-正丁基-3-甲基六氟磷酸盐([bmim]PF₆)能促进四氟硼酸铜催化一系列芳醛和乙酸酐反应, 以83%～97%的产率生成相应的1,1-二乙酸酯. 在离子液体[bmim]PF₆存在情况下, 催化剂活性远远高于无离子液体存在下的活性. 催化剂用量仅需 0.2 mol%就能使反应顺利进行, 远远少于文献报道的其它催化剂的用量, 反应在3～20 min内完成. 实验结果表明该法催化剂用量少、产率高、反应时间短、离子液体可重复使用、对环境友好.     

Catalytic Asymmetric Coupling of 2-Naphthols by Chiral Tridentate Oxovanadium(IV) Complexes

A series of chiral oxovanadium(IV) complexes derived from tridentate N-3,5-substituted-, N-3,4-benzo-and N-5,6-benzo-salicylidene-α-amino acids can serve as efficient catalysts for the enantioselective oxidative couplings of various 3-, 6-, and 7-substituted 2-naphthols under O2. The best scenario involves the use of a vanadyl complex arising from 2-hydroxy-l-naphthaldehyde and valine (or phenylalanine) in CCl4, leading to BINOLs in good yields (75-100%) and with enantioselectivities of up to 68%.     

新型手性钌络合物的合成、表征及其催化不对称环氧化

合成了一系列含手性联吡啶的钌(Ⅲ)络合物，并对其进行了IR、UV-Vis、CD、电导率等表征。初步考察了其对苯乙烯的不对称催化环氧化性能，获得最高达60％的e.e.值。     

Intermediates of Asymmetric Oxidation Processes Catalyzed by Vanadium(V) Complexes

The [VO(acac)₂]/Schiff base [R-2-(N-3,5-di-tert-butylsalicylidene)amino-2-phenyl-1-ethanol, S-2-(N-3,5-di-tert-butylsalicylidene)amino-3,3-dimethyl-1-butanol, S-2-(N-3,5-di-tert-butylsalicylidene)amino-3-methyl-1-butanol, or R-2-(N-3,5-di-tert-butylsalicylidene)amino-3-phenyl-1-propanol]/H₂O₂ catalytic systems for the asymmetric oxidation of sulfides and the [VO(acac)₂]/(3bR,4aR)-2-(3,4,4-trimethyl-3b,4,4a,5-tetrahydrocyclopropa[3,4]cyclopenta[1,2-c]pyrazol-1-yl)ethanol/tert-butyl hydroperoxide/TBHP and VO(OAlkyl)₃/[2,2]paracyclophane-4-carboxylic acid N-(1,1-dimethylethyl)-N-hydroxamide/TBHP catalytic systems for the asymmetric epoxidation of allylic alcohols were studied using ¹³C, ⁵¹V, and ¹⁷O NMR spectroscopy. The key intermediates of these systems (peroxo and alkylperoxo complexes of vanadium(V)) were detected, their structures in solution were studied, and the reactivity was evaluated.     

Soluble Monometallic Salen Complexes Derived from O‐functionalized Salicylaldehydes as Metalloligands for the Synthesis of Heterobimetallic Complexes

The reaction of 2,3‐diamino‐2,3‐dimethylbutane (tmen) with 3‐hydroxysalicylaldehyde (3hsal), 4‐hydroxysalicylaldehyde (4hsal), and 5‐hydroxysalicylaldehyde (5hsal) or 3‐carboxysalicylaldehyde (3csal) gave the hydroxy‐functionalized salen ligands H₄3hsaltmen, H₄4hsaltmen and H₄5hsaltmen, or the 3‐carboxy‐functionalized ligand H₄3csaltmen, which were characterized by ¹H, ¹³C{¹H} NMR and IR spectroscopy. The nickel(II) and copper(II) complexes [Ni(H₂3hsaltmen)], [Ni(H₂4hsaltmen)], [Ni(H₂5hsaltmen)], [Cu(H₂3hsaltmen)] and [Cu(H₂4hsaltmen)] were synthesized in high yield (78–99 %) starting from H₄3hsaltmen, H₄4hsaltmen and H₄5hsaltmen and the corresponding metal(II) acetates. The complexes are soluble in acetone, ethanol, methanol, thf and dmso. The reaction of H₄3csaltmen and nickel(II) acetate gave [Ni(H₂3csaltmen)] in 40 % yield. The disodium salt of the corresponding copper(II) complex [Cu(Na₂3csaltmen)] was obtained in 66 % yield in a template reaction from 3‐carboxysalicylaldehyde, tmen, copper(II) acetate and sodium hydroxide, and was characterized by EPR spectroscopy and mass spectrometry. All complexes were identified by IR spectroscopy and elemental analysis, the nickel complexes also by NMR spectroscopy, and [Ni(H₂3hsaltmen)], [Ni(H₂4hsaltmen)] and [Ni(H₂3csaltmen)] by X‐ray crystallography. The homobinuclear copper complex [Cu₂(3hsaltmen)] was prepared in 91 % yield from H₄3hsaltmen, two equivalents of Cu(CH₃COO)₂·H₂O and four equivalents of LiOH·H₂O and was characterized by IR spectroscopy, elemental analysis and mass spectrometry. The trinuclear complex [Zr{Ni(3hsaltmen)}₂] was obtained from [Zr(NEt₂)₄] and [Ni(H₂3hsaltmen)] (ratio 1:2) and characterized by FAB and APPI mass spectrometry and X‐ray crystallography. The redox potential of the trinuclear complex [Zr{Ni(3hsaltmen)}₂] is shifted by 0.04 V to positive potential compared to [Ni(H₂3hsaltmen)], while the redox potential of the binuclear copper complex [Cu₂(3hsaltmen)] is shifted by 0.22 V to negative potential compared to [Cu(H₂3hsaltmen)].     

Catalytic, Asymmetric Cyclopropanation of Diphenylethene Mediated by Chiral Copper-(Schiff Base) Complexes

Asymmetric cyclopropanation of diphenylethene with diazoacetates was catalyzed by new copper-(Schiff base) complexes. The effects of the substituents in substituted salicylaldehyde on the ee's were studied, and a 94.5% ee was achieved. This revised version was published online in June 2006 with corrections to the Cover Date.     

Asymmetric Synthesis of Planar Chiral (Arene)tricarbonylchromium Complexes via Enantioselective Deprotonation by Conformationally Constrained Chiral Lithium‐Amide Bases

Enantioselective lithiation/electrophile addition reactions with eight chiral Li‐amide bases, 1 – 8 , and five [Cr(arene)(CO)₃] complexes, 9 – 13 , were investigated. Restriction of conformational freedom in the chiral Li‐amide base Li‐ 1 , in general, did not result in an increase in asymmetric induction. A new route to enantiomerically enriched (75 – 92%) planar chiral ortho‐substituted benzaldehyde complexes via enantioselective lithiation of benzaldimine complexes 16 and 17 is reported. Within the (1S)‐enantiomer series of o‐substituted benzaldehyde complexes 18a – d , the sign of the specific rotation, [α], is found to be positive, except for the trimethylstannyl derivative 18b . This is interpreted in terms of a reversed conformation of the aldehyde group.     

Synthesis of Titanium (IV) Complexes with Schiff‐base Ligand and Their Catalytic Activities for Polymerization of Ethylene and Styrene

Reaction of titanium (IV) isopropoxide with the unusual land of Shiff‐base in 1:1 molar ratio gives a variety of new derivatives of titanium (IV) in high yield. These complexes were characterized by elemental analyses, IR, MS and ¹H NMR. It was noteworthy to find that all these complexes were active for polymerizations of ethylene and styrene when activated by a Lewis acid cocatalyst (MAO).     

Synthesis and Characterization of Iridium(V) Coordination Complexes With an N,O‐Donor Organic Ligand

We have prepared and fully characterized two isomers of [Ir^IV(dpyp)₂] (dpyp=meso‐2,4‐di(2‐pyridinyl)‐2,4‐pentanediolate). These complexes can cleanly oxidize to [Ir^V(dpyp)₂]⁺, which to our knowledge represent the first mononuclear coordination complexes of Ir^V in an N,O‐donor environment. One isomer has been fully characterized in the Ir^V state, including by X‐ray crystallography, XPS, and DFT calculations, all of which confirm metal‐centered oxidation. The unprecedented stability of these Ir^V complexes is ascribed to the exceptional donor strength of the ligands, their resistance to oxidative degradation, and the presence of four highly donor alkoxide groups in a plane, which breaks the degeneracy of the d‐orbitals and favors oxidation.     

Synthesis of Chiral Tertiary Boronic Esters by Oxime‐Directed Catalytic Asymmetric Hydroboration

Chiral boronic esters are useful intermediates in asymmetric synthesis. We have previously shown that carbonyl‐directed catalytic asymmetric hydroboration (CAHB) is an efficient approach to the synthesis of functionalized primary and secondary chiral boronic esters. We now report that the oxime‐directed CAHB of alkyl‐substituted methylidene and trisubstituted alkene substrates by pinacolborane (pinBH) affords oxime‐containing chiral tertiary boronic esters with yields up to 87 % and enantiomeric ratios up to 96:4 e.r. The utility of the method is demonstrated by the formation of chiral diols and O‐substituted hydroxylamines, the generation of quaternary carbon stereocenters through carbon–carbon coupling reactions, and the preparation of chiral 3,4,4‐trisubstituted isoxazolines.     

A Rapid and Convenient Synthesis of 1,1-Diacetates from Aldehydes and Acetic Anhydride Catalyzed by PVC-FeCl3 Catalyst

A variety of aldehydes can be converted into 1,1-diacetates rapidly and conveniently in the presence of catalytic amounts of poly(vinyl chloride) supported ferric chloride reagent at room temperature in excellent yields.     

手性Salen Mn(Ⅲ)配合物催化NaOCl不对称环氧化苯乙烯反应

手性Salen Mn(Ⅲ)配合物催化NaOCl不对称环氧化苯乙烯反应;不对称环氧化;Salen Mn(Ⅲ)配合物;苯乙烯;NaOCl     

Asymmetric Synthesis of 1,4‐Dicarbonyl Compounds from Aldehydes by Hydrogen Atom Transfer Photocatalysis and Chiral Lewis Acid Catalysis

Enantioenriched 1,4‐dicarbonyl compounds are versatile synthons in natural product and pharmaceutical drug synthesis. We herein report a mild pathway for the efficient enantioselective synthesis of these compounds directly from aldehydes through synergistic cooperation between a neutral eosin Y hydrogen atom transfer photocatalyst and a chiral rhodium Lewis acid catalyst. This method is distinguished by its operational simplicity, abundant feedstocks, atom economy, and ability to generate products in high yields (up to 99 %) and high enantioselectivity (up to 99 % ee).     

六水合三氯化铁在离子液体1-正丁基-3-甲基六氟磷酸鎓盐中催化芳醛和乙酸酐合成1,1-二乙酸酯

在室温条件下,六水合三氯化铁在离子液体1-正丁基-3-甲基六氟磷酸鎓盐([bmim]Pf6)中能催化一系列芳醛和乙酸酐反应,以85%～97%的产率生成相应的1,1-二乙酸酯.