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1.
《Tetrahedron: Asymmetry》1998,9(2):285-292
The title compound 3, an intermediate in the synthesis of fluorocarbapenems, is obtained with high stereocontrol by the condensation of (R)-(+)-ethyl 4,4,4-trifluoro-3-hydroxybutanoate with N-trimethylsilyl cinnamylidenimine. X-Ray diffraction analysis of the condensation product and chemical correlations allowed the unambiguous determination of the absolute configuration.  相似文献   

2.
A new palladium compound [Pd(NH3)4][cis-Pd(NH3)2(SO3)2][Pd(NH3)3(SO3)] · H2O (I) was synthesized and its structure was studied by X-ray powder diffraction method. In the course of the synthesis, the initial trans-diamminesulfite anionic complex is transformed into the cis-configuration. Further heating in aqueous solution results in isomerization of a substance into a neutral complex [Pd(NH3)3(SO3)]. Crystals I are triclinic: a = 10.3297(2) Å, b = 14.1062(3) Å, c = 6.8531(1) Å, = 101.36(0)°, = 92.74(0)°, = 92.71(0)°, space group P1¯. Structure I consists of the columns with alternating cis-[Pd(NH3)2(SO3)2]2– and [Pd(NH3)3(SO3)] complexes and [Pd(NH3)4]2+ ions between the columns.  相似文献   

3.
Journal of Structural Chemistry - New complex salts [Pd(NH3)4][Pd(NH3)3NO2][CrOx3]·H2O I, [Pd(NH3)4][Pd(NH3)3NO2][CoOx3]·H2O II, and a series of solid solutions...  相似文献   

4.
The structure of double complex salts [Pd(NH3)3(NO2)][Rh(NH3)2(NO2)4] and [PdEn2][Rh(NH3)(NO2)5]·0.75H2O is determined by single crystal X-ray diffraction. In the structures, the main structural moieties are identified.  相似文献   

5.
New coordination compounds: [PtIIQ] and [PtIV–CrIIIQ2], where Q = quercetin, were isolated from the [Pt(NH3)2Cl2–quercetin] and [Pt(NH3)2Cl2–CrVI–quercetin] systems, respectively. Structures are proposed on the basis of i.r., n.m.r. and deconvoluted electronic spectra.  相似文献   

6.
《Tetrahedron: Asymmetry》1999,10(18):3479-3482
A new approach towards the enantioselective synthesis of (2S,2′R)-erythro-methylphenidate (1) is described. The key step in the synthesis utilizes Evans' 4-substituted-2-oxazolidinone chiral auxiliary to control the diastereofacial selectivity in the hydrogenation of enamine intermediate 6, yielding the hydrogenated product 7 with excellent diastereoselectivity. Methanolysis of 7 afforded 1 with excellent enantiopurity.  相似文献   

7.
In our prior studies,3′,4′-di-O-(S)-camphanoyl-(+)-cis-khellactone(DCK,1,Figure1)and its derivatives including mono-and di-substituted DCK analogs were identified as a novel class of potent anti-HIV agents1-4.Because of its high potency and efficient syn-thesis,4-methyl-DCK25was chosen as a drug candidate for preclinical studies.How-ever,the low solubility and poor oral bioavailability of4-methyl-DCK limited its further development.Because high molecular hydrophobicity might be one re…  相似文献   

8.
The study of the system xSb2O3–(1 ? x)Bi2O3–6(NH4)2HPO4 has been carried out to identify the phases and simulate the mechanisms of their formation, using the technique of thermal analysis in association with X-ray diffractometry. The main stages observed during thermal treatment of the samples include: (1) elimination of water and ammonia leading to the formation of (NH4)5P3O10; (2) reaction of the latter with M 2 III O3 and the formation of acidic polyphosphates M 2 III H2P3O10; (3) their dehydration with the formation of the polyphosphates MIII(PO3)3. Then Sb(PO3)3 decomposes giving SbPO4 and P2O5. In the presence of excessive P2O5, two moles of Bi(PO3)3 condensate into oxophosphates Bi2P4O13 and BiP5O14. The data of thermal analysis match with the composition of intermediate and final products. The hygroscopicity of the samples diminishes with growing bismuth content.  相似文献   

9.
用从头计算法在HF/6-31G*基组水平上研究了NH4++NH3→NH3+NH4+,NH4++NH2CH3→NH3+NH3CH3+,NH4++NH(CH3)2→NH3+NH2(CH3)2+以及NH3CH3++NH2CH3→NH2CH3+NH3CH3+等4个体系的质子传递反应的机理.结果表明:(1)上述质子传递反应均具有双阱型的势能面,质子沿N(1)、N(2)连线直接传递;(2)质子受体分子中的甲基对质子传递起促进作用,而质子给体离子中的甲基则阻碍质子的传递。  相似文献   

10.
无机-有机杂化钒氧酸盐由于其结构的多样性以及在催化、医药、光、电、磁等材料领域中的应用前景而受到人们的广泛关注。近年来这一研究领域的重大进步是将有机氮配体或者过渡金属配合物直接连接到矾氧骨架上以获得各种新奇结构。合成出许多属于L/V/O、MXLY/V/O、L/P/V/O和MXLY  相似文献   

11.
N-tosyl-2- and N-tosyl-4-halogen-substituted derivatives of 2-(1-methylbut-2-en-1-yl)aniline were synthesized and their molecular iodine-mediated cyclization was investigated. The cyclization upon interaction of N-tosyl-6-methyl-2-(1-methylbut-2-en-1-yl)aniline with molecular iodine in methyl tert-butyl ether or acetonitrile was studied, as well as the interaction of this sulfonamide with N-bromosucinimide in dichloromethane. Synthesized (2R*,3R*)- and (2R*,3S*)-N-arylsulfonyl-2-(1-halogenoethyl)-3-methylindoline derivatives showed cytotoxic activity against HEK293 cells, SH-SY5Y, Jurkat, and HepG2 cell lines. The compounds (2R*,3S*)-N-arylsulfonyl-7-bromo-2-(1-halogenoethyl)-3-methylindoline cis- 4a , stereoisomeric (2R*,3R*)-trans- 4h and (2R*,3S*)-N-tosyl-7-chloro-2-(1-halogenoethyl)-3-methylindoline cis- 4h demonstrated selective toxicity against SH-SY5Y cell line (IC50 ≈ 3 ÷ 5 μM), and did not affect HEK293, Jurkat, and HepG2 cells.  相似文献   

12.
农作物不仅需要吸收C、H、O、N、P、K、Ca、Mg等营养元素,而且还需要吸收B、Mn、Zn等营养元素,以维持它们正常生长的需要.尿素是一种含氮量很高(46.60%)、性能很好的氮肥,而硼化合物又是一种很重要的微量元素肥料.因此,研究尿素与硼化合物间的相互作用,以得到既含氮又含硼的一种化合物,是一种很有意义的工作。目前,国外已开展了尿素与硼酸间相互作用的研究工作.研究结果表明,在一定条  相似文献   

13.
After a short survey of what is the present state of the cyclophosphates associated with the organic molecule NH2(CH2)4NH2, we report chemical preparation and crystal structure for a new example of such compounds. [NH3(CH2)4NH3]2P4O12.2H2O is monoclinic (S.G. : P21/n), with Z = 2 and the following unit-cell parameters : a = 7.6728(8) Å, b = 18.962(3) Å, c = 7.9789(9) Å β = 111.751(9)°. Bidimensional layer arrangement of P4O12 rings connected to the water molecules thanks to weak H-bonds run parallel to the ab plane. The organic groupements located between these inorganic planes perform the three-dimensional cohesion by NH····O hydrogen bonds.  相似文献   

14.
Compounds [Rh(NH3)5(NO2)](NO3)2·H2O (I) with a = 7.6230(3) Å, b = 7.6230(3) Å, c = 10.3584(4) Å, space group I-42m, Z = 2, d calc = 2.026 g/cm3, V = 601.93(4) Å3, Rh-NH3 eq = 2.074 Å, Rh-NH3 ax (NO2) = 2.048 Å; [Rh(NH3)5(NO2)][Pd(NO2)4] (II) with a = 8.095(3) Å, b = 22.422(8) Å, c = 7.887(3) Å, β = 98.559(17)°, space group Cc, Z = 4, d calc = 2.461 g/cm3, V = 1415.6(9) Å3, Rh-NH3 eq = 2.069 Å, Rh-NH3 ax = 2.090 Å, Rh-NO2 = 2.002 Å; K2[Rh(NH3)(NO2)5]·H2O (III) with a = 7.5177(5) Å, b = 20.9856(15) Å, c = 7.7017(5) Å, space group Cmc21, Z = 4, d calc = 2.439 g/cm3, V = 1215.05(14) Å3, Rh-NH3 ax (NO2) = 2.094 Å, Rh-NO2 eq = 2.030 Å are synthesized and studied using single crystal X-ray diffraction.  相似文献   

15.
《Tetrahedron: Asymmetry》2014,25(4):318-326
1-n-Propoxy-3-methyl-3-phospholene 1-oxide was prepared in optically active form by extending resolution methods applying (−)-(4R,5R)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane (‘TADDOL’) and (−)-(2R,3R)-α,α,α′,α′-tetraphenyl-1,4-dioxaspiro[4.5]decan-2,3-dimethanol (‘spiro-TADDOL’), as well as the acidic and neutral Ca2+ salts of (−)-O,O′-dibenzoyl- and (−)-O,O′-di-p-toluoyl-(2R,3R)-tartaric acid. In one case, the diastereomeric complex could be identified by single crystal X-ray analysis. The absolute P-configuration of the enantiomers of the phospholene oxide was also determined by CD spectroscopy.  相似文献   

16.
首次报告了在分子束条件下,研究Ar(3P0,2)+NH3碰撞解离反应·利用单光子计数方法进行测量,获得了部分转动分辨的初生态产物NH2(A2A1)→(X2B1)发射谱,并详细地进行了标识·发现主要为[HTSS](0,v 2',0)→(0,0,0)跃迁(v'≤5,K'a≤6,J'≤10)。通过对部分分辨较好的光谱范围进行了模拟,得到反应生成的NH2(A2A1,v'=2,k'a =1)态绕b/c轴的转动温度为1050K,高于母体分子NH3的转动温度300K。由亚稳态碰撞传能电子交换机理认为这是由于碰撞对手Ar和母体NH3分离时反冲作用的结果。碰撞传能解离机理和光解过程不同,后者仅观察到轴的转动激发。  相似文献   

17.
18.
用密度泛函理论UB3LYP/6-31G(d,p)方法研究了二甲胺自由基(CH3)2N及其质子化离子(CH3)2NH 的构象和超精细结构.在由构象研究得到的两种自由基的最稳定结构上,用密度泛函的UB3LYP和UB3PW91方法及从头计算的UHF、UMP2(FULL)方法计算了α-质子、β-质子和N核上的超精细偶合常数A(Hα)、A(Hβ)和A(N)结果表明:两种自由基中甲基内旋转的位垒均很低,分别为0.46kJ·mol-1((CH3)2NH )和2.6kJ·mol-1((CH3)2N).UB3LYP/6-31G(d,p)和UB3PW91/6-31G(d,p)计算的A(Hα)、A(Hβ)和A(N)与ESR实验结果符合得很好,UMP2/6-31G(d,p)方法的计算值与实验值符合得也较好.  相似文献   

19.
The electrochemical properties and catalytic activity of a Co(II) complex with the optically active Schiff base derived from (1R,2R)-(–)-cyclohexanediamine and salicylaldehyde have been studied in non-aqueous solutions. When dissolved in deoxygenated non-aqueous solutions, the complex exhibits reversible redox properties for the Co(II)/Co(III) couple. Electrochemical reduction of oxygen and oxidation of cobalt(II) was observed on cyclic voltammograms of solutions containing both dioxygen and the Schiff base-cobalt(II) complex. An anodically formed film on a platinum electrode, studied by means of X-ray photoelectron spectroscopy, revealed the presence of the oxidized Co(III) species. Cyclic voltammetry of oxygenated solutions examined after a period of time indicates an electrochemical activity of coordinated superoxo/peroxo species in the 0.7–1.1 V potential range. In the presence of 4-methyl-1-cyclohexene the cyclic voltammetry curves reveal changes similar to those caused by the removal of oxygen. The GC-MS technique was used to identify some of the products formed by the catalytic oxidation of cyclohexene and 4-methyl-1-cyclohexene. Electronic Publication  相似文献   

20.
Infrared and Raman Spectra of single crystal and polycrystalline samples of NH3(CH2)2NH3(H2PO4)2 and of its deuterated polycrystalline derivative have been recorded at 298 K. All the observed bands have been assigned using group theory. The IR and Raman spectra are consistent with the presence of strong OH⋯O hydrogen bonds.  相似文献   

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