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1.
BinFU DaMingDU QingXIA 《中国化学快报》2004,15(4):383-385
The synthesis of bis(oxazoline) dicarboxylate derivatives was investigated.Diethyl-aminosulfur trifluoride (DAST) was used as a convenient cyclization reagent in the synthesis of bis(oxazoline) dicarboxylate derivatives,which can not be obtained by the general method using MsC1 and Et3N as dehydrating cyclization reagent. 相似文献
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New bis(oxazoline) ligands (BOXs) containing biaryl substitutents at the C-4 position and H or CH2OR substituents at the C-5 position have been synthesized using Suzuki cross-coupling as the main tool for structural diversity. Copper, zinc, and palladium complexes of the prepared BOXs have been evaluated in the following catalytic asymmetric processes: Acylation with kinetic resolution of trans-1,2-cyclohexanediol (Cu), enantioselective Friedel-Crafts alkylation of indole (Zn), and enantioselective alkylation of 3-acetoxy-1,3-diphenylpropene (Pd). 相似文献
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The novel C2‐symmetric sulfur‐containing chiral bis(oxazoline) compound has been synthesized and characterized by X‐ray crystallography. Highly enantioselective and diastereoselective cyclopropanation reactions have been performed using the copper‐bis(oxazoline) catalyst. 相似文献
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The serendipitous isolation of an unusual protonated bis(oxazoline) prompted us to discuss the role of H+ on the kinetics and thermodynamics of the equilibrium between its ketimine and enamine forms. X-ray diffraction analysis revealed that the protonated bis(oxazoline) is in the Z-enamine form, the unipositive charge is counterbalanced by [(FeCl3)2O]2− and [FeCl4]− anions. DFT calculation at the BP86/TZVP level showed that relative stability of enamine tautomer versus ketimine tautomer increases with the protonation of the nitrogen atom of the oxazolidine ring. At the same time, the barrier energy of tautomerism decreases. 相似文献
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Vesna ?aplar Zlata Raza Vladislav Tomiši? Josip Po?ar Mladen ?ini? 《Tetrahedron》2004,60(37):8079-8087
Silver(I) and copper(I) complexes of C2-symmetric bis(oxazoline) ligands were studied by UV, NMR, IR, EPR and ES-MS spectroscopies. The stability constants of the Ag-1a and Ag-1b complexes with 1:1 and 1:2 stoichiometries in acetonitrile were determined by NMR spectrometric titrations. The evidence of tetrahedral coordination for complex (Ag(1a)2(+ was obtained from the complexation induced shifts (CIS) and NOEs. Mass spectra revealed the Cu(II) mediated oxidation of methylene bridge in copper complexes of 1a and 1b, which was in accordance with the UV, NMR, IR and EPR findings. The efficiency of Cu(I) complexes of methylene-bridged 1,5-bis(oxazoline)s 1 as chiral catalysts in stereoselective cyclopropanation of styrene with ethyl diazoacetate, was compared to that of the dialkylmethylene-bridged 1,5-bis(oxazoline)s 2. 相似文献
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The electron impact mass spectra of ten new C2-symmetric chiral bis(oxazoline) and bis(thiazoline) have been studied. Bis(thiazoline) and bis(oxazoline) possess the same fragmentation mechanism under EI conditions. An unusual fragmentation pathway has been found in the compounds studied. Due to the presence of phenyl group, compounds 6 and 10 undergo a new fragmentation pathway except for the common way as the other eight compounds.Mass analyzed ion kinetic energy spectra experiments and high resolution accurate mass measurement were conducted to confirm the proposed fragmentation pathways. 相似文献
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Anna Kozakiewicz Magorzata Ullrich Mirosaw Weniak Andrzej Wojtczak 《Journal of molecular catalysis. A, Chemical》2008,286(1-2):106-113
Purpose of the research was to determine the activity of chiral bis(sulfonamide) ligands derived from camphor in the addition of diethylzinc to benzaldehyde. Chiral bis(ketosulfonamides) and bis(hydroxysulfonamides), have been synthesized in a reaction of diamines with camphorsulfonic acid chloride. Their activity in a reaction of asymmetric addition of dialkylzinc to benzaldehyde in a presence of titanium(IV) tetraisopropoxide was determined. The bis(ketosulfonamide) ligands reveal low enantioselectivity, with the ee% not exceeding 12%. The bis(hydroxysulfonamides) reveal much higher asymmetric induction in the investigated ZnEt2 addition. The best enantiomeric excess (62%) has been observed for bis(hydroxysulfonamide) obtained from 1,3-diaminepropane. The yields of the reaction obtained after 18 h are 92–96%. Crystal structures have been solved for bis(ketosulfonamide) ligands obtained from diamines based on C2 to C4 chain. The (2R) configuration in the rings systems of bis(hydroxysulfonamide) containing the C3 bridge was also determined by the crystal structure analysis. The sulfonamides have been characterized by IR, 1H and 13C NMR. 相似文献
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Yoshimi HirokawaMaria Kitamura Chiharu KatoYuki Kurata Naoyoshi Maezaki 《Tetrahedron letters》2011,52(5):581-583
We have achieved the total synthesis of (±)- and (+)-eupomatilone 2 isolated from the Australian shrub Eupomatia bennettii. The key reaction was an asymmetric [2,3]-Wittig rearrangement employing a bis(oxazoline) chiral ligand. Although the highly oxygenated biphenylmethyl ether exhibited considerably lowered enantioselectivity as compared with the non-substituted biphenylmethyl ether, the selectivity was improved to 89% ee by using n-BuLi and ether as the base and the co-solvent, respectively. 相似文献
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Chiral bis(oxazoline) ligands have been applied in many enatioselective reactions. Recently, studies of the immobilization of bis(oxazoline) on both soluble and insoluble supports have been of great interest. Among the different methods to anchor the homogeneous catalysts, a soluble, polymer-supported catalyst usually achieves higher stereoselectivity and activity because the catalysis can be separated and recycled via simple methods such as solvent precipitation. Dendrimers are highly branche… 相似文献
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A series of simple and new C2-symmetric diphenylmethylidene malonate-type bis(oxazoline) ligands were synthesized and applied to the Friedel-Crafts reaction and allylic alkylation. The Cu(II) complex of ligand 4b bearing the benzyl group afforded good to excellent enantioselectivity for the F-C adducts (up to >99% ee) between indole and alkylidene malonate, and the palladium complex of ligand 4c bearing the phenyl group afforded excellent enantioselectivity (up to 94% ee) for the allylic alkylation product. 相似文献
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《Journal of heterocyclic chemistry》2017,54(2):1611-1618
Synthesis of some new bis(isoxazoline) derivatives has been described from terepthaldehyde derived bis(nitrones) using microwave irradiation via 1,3‐dipolar cycloaddition reaction. Bis(isoxazoline) derivatives in turn successfully converted into new bis(aziridine) derivatives via Baldwin rearrangement. Simple reaction methodology, non involvement of catalysts, and good to excellent yields are the important features noticed in this synthesis. 相似文献
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《Tetrahedron letters》2014,55(50):6803-6807
Catalytic asymmetric Diels–Alder reactions of N-allenoyloxazolidinones were investigated. Various chiral metal–bis(oxazoline) and metal–pyridinebis(oxazoline) complexes were screened. Cu(SbF6)2(H2O)2(t-BuBox) was found to be the most effective catalyst, giving the product in high yield, enantioselectivity, and endo:exo selectivity. The relative reactivity between N-allenoyloxazolidinones and N-alkenoyloxazolidinones was also investigated. A model for stereoinduction was proposed to account for the enantioselectivity and endo:exo selectivity. 相似文献
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M. Rosa CastilloSergio Castillón Carmen ClaverJosé M. Fraile Aitor GualMarta Martín José A. Mayoral Eduardo Sola 《Tetrahedron》2011,67(30):5402-5408
NPN ligands based on the bis(oxazoline) skeleton can be prepared by a divergent method, which allows a high modularity both in the type of phosphorous group (phosphinite, phosphate, phosphane) and the substitution in the methylene bridge. The Pd complexes of these ligands can efficiently promote the allylic substitution both in molecular solvents and ionic liquids, with important effect of the nature of ligand, which also controls the partial recovery of the Pd catalyst in ionic liquid. 相似文献
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采用DSC方法研究了聚对苯二甲酸乙二酯 (PET)和热致性液晶共聚酯 6 0PHB PET (LCP)体系在少量扩链剂双 (2 唑啉 ) (BOZ)存在下形成的反应性共混物的非等温结晶动力学 .结果表明反应性共混物的Avrami指数均在 3 0~ 4 5之间 ,BOZ的加入使反应共混物中PET组分的结晶速率降低 ;表明BOZ对酯交换的促进作用 ,使所生成的共聚酯中PET嵌段的数均序列长度变短 ,而使结晶在某种程度上较为困难 ,但对体系的成核和结晶生长机理无明显影响 .结果还表明 ,随冷却速率的增大结晶峰向低温方向移动 相似文献
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Synthesis of New Chiral C2-Symmetrical Bis(oxazoline )Compounds 总被引:2,自引:0,他引:2
New chiral C2-symmetrical bis(oxazoline)compounds bearing one isobutyl-,secbutyl-benzyl- or isopropyl-substituent at the 4-position have been prepared and characterized. 相似文献
20.
In recent years, C2-symmetric chiral bis (oxazoline) ligand-metal complexes have received a great of attention through their use in various catalytic processes[1-2]. Since the early 1990s, many impressive enantioselective carbon-carbon bond forming reactions, aziridination reactions, hydrosilylations, oxidations and reductions have been recorded using bis (oxazoline)-metal complexes with wide structural diversity[3-4]. The latest review is intended to focus on the recent developments of bis(oxazoline) ligand-metal catalyzed asymmetric reactions and their applications in organic synthesis. Herein we intend to report the synthesis of a new type of chiral bis(oxazoline), 1,3-bis(oxazolinyl)benzene. Application of their asymmetric catalysis is under working. 相似文献