Novel products from attempted michael addition to 1-methyl-1,2,5,6-tetrahydropyridine-4-carbonitrile

The reaction of some phenols with the title compound, in the presence of sodium, gives 2-(2-hydroxyaryl_piperidine derivatives. Geometrical isomers have been separated, which differ in having an equatorial (A) or axial (B) cyano group on the piperidine chair (the methyl and aryl groups are equatorial in both forms). The x-ray crystallographic structures of an example of each of A and B are reported and the proton NMR spectra are assigned.     

Monoximes and dioximes of 2,1,3-benzothiadiazole dignes

NMR spectra, in organic solvents, and dissociation constants in water, have been determined for a series of monoximes, dioximes and mono-O-methyldioximes of 2,1,3-benzothiazole-4,5 and 4,7-dione. On the basis of NMR data “4 - hydroxy - 5 - nitroso-, 4 - hydroxy - 7 - nitroso- and 5 - hydroxy - 4 - nitroso -2,1,3- benzothiadiazole” exist predominantly in quinonemonoxime forms. Configurations were assigned to geometrical isomers. The 4,5- and 4,7 - di - O - methyidioximinobenzothiadiazoles were also investigated. Four and two geometrical isomers of the 4,5- and 4,7-derivatives, respectively, have been separated, and the physical and spectral properties of each isomer are described.     

Structural isomer differentiation of 1,6-diaza-3,8-dioxabicyclo[4.4.1]undecane and N,N'-methylenebis(oxazolidine) by mass spectrometry

The title compound types are structural isomers. The absence of literature studies dealing with the mass spectrometric gas-phase behavior of such compounds prompted a search for the best conditions for differentiation between the two prototype examples (R,R)-5,10-diphenyl-1,6-diaza-3,8-dioxabi-cyclo[4.4.1]undecane and N,N'-methylenebis[(R)-4-phenyloxazolidine]. Attempts to differentiate between the isomers by NMR were inconclusive and X-ray crystallography had to be used. The best mass spectrometric results were obtained using gas-phase ionization techniques, particularly chemical ionization, whereby protonated molecules were observed. The fragmentation pathways were elucidated from MS/MS studies and from experiments performed on hexadeuterated samples of each compound.     

Complete 1H and 13C NMR spectral assignment of cis- and trans- 3-(2-[2-(4-methylphenyl)ethenyl]phenyl])sydnones

1H and 13C NMR spectra of cis- and trans-3-(2-[2-(4-methylphenyl)ethenyl]phenyl])sydnones, the first stilbene-substituted mezoionic oxadiazolium rings, were fully assigned combining the information in various solvents, such as deuterated benzene, acetone and chloroform, using 2D NMR techniques.     

Structure and spectral property of 8-(2-(5-(4-methylphenyl)-2-thienyl)vinyl)-10,10-dimethyl-10H-pyrido[1,2-a]indolium perchlorate

The title compound 8-(2-(5-(4-methylphenyl)-2-thienyl)vinyl)l-10,10-dimethyl-10H-pyrido[1,2-a]indolium perchlorate (3) has been synthesized by cycloaddition and condensation reactions, and characterized by elemental analysis, IR, ¹H NMR, and single-crystal X-ray diffraction. The crystal structure analysis exhibits that the molecule of 3 possesses good coplanarity, and the three rings (10H-pyrido[1,2-a]indolium, thienyl and phenyl) and vinyl moiety can make up a large conjugated system. Its UV-Vis and fluorescence spectra were measured, and found that it displays larger maximum absorptions and emission wavelengths in comparison with 8-(4-methylphenyl)vinyl analogue.     

On the proof and disproof of natural product stereostructures: characterization and analysis of a twenty-eight member stereoisomer library of murisolins and their Mosher ester derivatives

Characterizing a stereoisomer library of 28 of the 64 possible isomers of the acetogenin murisolin, including 24 of the 32 possible diastereomers, provides a complete picture of the spectra of this class of molecules. Remarkably, each of the 32 diastereomers exhibits one of only six sets of substantially identical (1)H NMR spectra under standard conditions. These spectra follow directly from a local symmetry analysis of the dihydroxy-THF fragment of the molecule and provide no information about the configuration about the hydroxybutenolide. Eighteen tris-Mosher ester derivatives of library members have been made, and their spectra were analyzed to give a complete picture of the usefulness of chiral derivatives. The tris-Mosher esters of the 64 isomers of murisolin will exhibit 40 sets of spectra: 16 isomers have unique spectra whereas 24 isomers share an identical spectrum with one other isomer. This identity occurs even though the pairs of compounds were already diastereomers (not enantiomers) before the derivatization. The complete set of spectra allows any murisolin or closely related compound to be narrowed to one or two structures by simple matching and without recourse to assignment and subtraction of resonances. The structure of murisolin was proved to be the 4R,15R,16R,19R,20R,34S isomer, whereas the assignment of 16,19-cis-murisolin as RRRSSS was changed to the RSSRRS diastereomer and murisolin A is suggested to be RSRRRS.     

Synthesis and structural characterization of a tetracopper(I) complex of 2,6-(bis(3- dimethylamino)-propyliminomethyl)-4- methylthiophenolate

The compound 2,6-diformyl-4-methylphenyl (1) has been made by hydrolysis of S-(2,6- diformyl-4-methylphenyl)dimethylthiocarbamate followed by oxidation with I₂. Condensation of 1 with 4 equiv. of 3-dimethylaminopropylamine and subsequent reduction with Na/benzophenone results in the sodium salt of the Schiff base binucleating ligand 2,6-(bis(3-dimethylamino)-propyliminomethyl)-4-methyl-thiophenolate (2, NaL). The ligand (L) binds 2 eq of Cu(I) and crystallizes from MeCN solution to give an air sensitive tetracopper(I) complex with the formula [Cu₄L₂(MeCN)](PF₆)₂ (3)·0.5 MeCN·0.25 MeOH as determined by X-ray crystallography. The complex contains three distorted trigonal planar and one distorted tetrahedral Cu¹ centers with Cu---S bond lengths short for their respective coordination geometries. In DMSO solution, ¹H NMR spectra of 3 reflect free ligand symmetry suggesting dissociation into dimers. Cyclic voltammetry of 3 in MeCN reveals one irreversible oxidation at 110 mV (vs SCE).     

Syntheses of O-(2-Acetamido-2-Deoxy-α-D-Galactopyranosyl)-Myo-Inositols

ABSTRACT

The structure of an O-(2-acetamido-2-deoxy-α-D-galactopyranosyl)-myo-inositol isolated from human pregnancy urine has previously been identified as that of 1-O-(2-acetamido-2-deoxy-α-D-galactopyranosyl)-myo-inositol. In order to ascertain the absolute configuration in the inositol part of the compound, the 1D- and 1L- isomers were synthesised. Since none of these two stereoisomers corresponded to the natural product, the corresponding 2-O-, the mixture of the two 1DL-4-O-, and 5-O- isomers were also synthesised. None of these gave ¹H NMR spectra corresponding to the natural product, the structure of which therefore remains unresolved.     

4-氨基-5-[2-(4-氯苯氧甲基)苯并咪唑-1-亚甲基]-1,2,4-三唑-3-硫酮的核磁共振研究

在无水乙醇和KOH存在下,将2-(4-氯苯氧甲基-1-苯并咪唑乙酰肼(1)与CS2反应,合成出了中间体酰肼二硫代甲酸钾盐.此中间体再与过量的水合肼反应,经环化得到一种新化合物4-氨基-5-[2-(4-氯苯氧甲基)苯并咪唑-1-亚甲基]-1,2,4-三唑-硫酮.采用元素分析、IR及NMR技术确定了新化合物的结构,并利用2...     

2-氨基-5-硫代-噻二唑啉-β-D-核呋喃糖苷的合成

2-氨基-5-硫代-1,3,4-噻二唑啉和1-O-乙酰-2,3,5-三-O-苯甲酰核呋喃糖通过熔融缩合和Vorbruggen缩合, 所得两个产物经^1H, ^1^3C NMR, 质谱以及X射线结晶学分析, 鉴定为位置异构体2-亚氨基-5-硫代-1,2,4-噻二唑啉-3-β-D-核呋喃糖苷和2-氨基-5-硫代-1,3,4-噻二唑啉-4-β-D-核呋喃糖苷。     

Electrocyclic Reactions of Siloles: A Combined Experimental and Theoretical Study

The reaction of 4‐chloro‐1,2‐dimethyl‐4‐supersilylsila‐1‐cyclopentene ( 2 a ) with Li[NiPr₂] at ?78 °C results in the formation of the formal 1,4‐addition product of the silacyclopentadiene derivative 3,4‐dimethyl‐1‐supersilylsila‐1,3‐cyclopentadiene ( 4 a ) with 2,3‐dimethyl‐4‐supersilylsila‐1,3‐cyclopentadiene ( 5 a ). In addition the respective adducts of the Diels–Alder reactions of 4 a + 4 a and 4 a + 5 a were obtained. Compound 4 a , which displays an s‐cis‐silacyclopentadiene configuration, reacts with cyclohexene to form the racemate of the [4+2] cycloadduct of 4 a and cyclohexene ( 9 ). In the reaction between 4 a and 2,3‐dimethylbutadiene, however, 4 a acted as silene as well as silacyclopentadiene to yield the [2+4] and [4+2] cycloadducts 10 and 11 , respectively. The constitutions of 9 , 10 , and 11 were confirmed by NMR spectroscopy and their crystal structures were determined. Reaction of 4‐chloro‐1,2‐dimethyl‐4‐tert‐butyl‐4‐silacyclopent‐1‐ene ( 2 c ) with KC₈ yielded the corresponding disilane ( 12 ), which was characterized by X‐ray crystal structure analysis (triclinic, P$\bar 1$ ). DFT calculations are used to unveil the mechanistic scenario underlying the observed reactivity.     

A cytotoxic triketone-phloroglucinol-bullatenone hybrid from Lophomyrtus bullata

Cytotoxic activity against the P388 cell line was seen in a crude extract of the New Zealand shrub Lophomyrtus bullata(Myrtaceae). Bioactivity-guided isolation led to a compound with NMR spectra complicated by the presence of two isomers. These crystallised together and an X-ray structure showed them to be stereoisomeric hybrids of triketone, phloroglucinol and bullatenone units. NMR measurements on the mixed isomers, as well as a cyclic ether produced from them by acid catalysed dehydration, were consistent with these structures. The natural products, named bullataketals A and B, have cytotoxic activity against the P388 cell line (IC(50) 1 microg ml(-1)), and antimicrobial activity against Bacillus subtilis.     

Conformational studies by dynamic NMR. 93.(1) Stereomutation,enantioseparation, and absolute configuration of the atropisomers of diarylbicyclononanes

The structure of 9-(4-methoxyphenyl)-9-(3-methylphenyl) bicyclo[3.3.1]nonane (1) has been determined by single-crystal X-ray diffraction, and the rotation barriers about the two aryl-C9 bonds have been measured by variable temperature NMR spectroscopy in solution. In the case of 9-(4-methoxyphenyl)-9-(1-naphthyl)bicyclo[3.3.1]nonane (3), the barrier involving the naphthyl-C9 rotation was found to be so high as to allow the physical separation of the two atropisomers by enantioselective HPLC at ambient temperature: the absolute configuration could be established on the basis of the corresponding CD spectra. It was also observed that the Ar-C9 rotation barriers of monoaryl-substituted nonanes are much lower than those of the corresponding diaryl-substituted nonanes.     

三—（2—甲基氮丙啶）氧化膦异构体的核磁共振和量子化学研究

三-(2-甲基氮丙啶)氧化膦(MAPO)为黄色油状液体,其化学性质活泼,可用作塑料、橡胶及造纸业中高分子化合物的交联剂等。本文对MAPO进行了~1H、~(13)C、~(15)N、~(31)P和~(17)O的核磁共振研究及量子化学计算。结果表明,该化合物存在4种异构体,其中2种为对映体,并得到了这4种异构体的几何构型。     

Dynamic NMR: A new procedure for the estimation of mixing times in the 2D EXSY experiments. A four-site exchange system studied by 1D and 2D EXSY spectroscopy

A procedure for the estimation of the mixing time between the last two 90° pulses in the classic three-pulse sequence NOESY/EXSY is proposed and tested and some considerations for the treatment of the two-dimensional (2D) ¹H NMR exchange spectra are given. The rate constants are thus obtained with reasonable precision. This procedure was followed to obtain the 2D spectra of the model compound α-[bis(dimethylamino)methylene]-4-nitrophenylacetonitrile, which represents a four-site exchange system. The barriers to restricted rotations found in this compound were also determined from one-dimensional (1D) ¹H NMR spectra, which were processed with the iterative complete lineshape analysis (CLSA) method. The double-fit approach was incorporated in the CLSA method. It is shown that the results from the 2D dynamic NMR spectral studies corroborate those obtained by the CLSA double-fit method.     

新型嘧啶单环类非经典叶酸拮抗剂的合成及抗肿瘤活性研究

以课题组前期设计合成的非经典叶酸拮抗剂6-(4'-甲基苯乙基)-N5-氯乙酰基-2,4-二氨基哌啶并[3,2-d]嘧啶(wm-8.2)为先导化合物,将wm-8.2中的哌啶并嘧啶双环结构简化为嘧啶单环结构,以提高分子柔韧性并简化分子结构,根据6-位空间占位设计6-H和6-甲基两个系列,考察了不同桥链长度和不同芳香杂环侧链对抗肿瘤活性的影响.同时对具有叶酸抑制剂分子结构特征的关键中间体进行活性对比测定,研究了N(5)位氯乙酰基对活性的影响.两个系列目标化合物和关键中间体共36个化合物的结构均经1H NMR,13C NMR和MS确证.生物活性测定表明,6位为甲基的化合物中,具有三碳桥链及对甲基苯环侧链的6-甲基-2,4-二氨基-5-(N-(4-甲基苯基)丙基-N-(2-氯乙酰基))氨基嘧啶(6b-3)具有最好的HL-60、A549和HCT116细胞增殖抑制活性,IC50分别为0.25,0.83和0.63μmol?L^-1.化合物6b-3在N(5)位氯乙酰基取代之前的关键中间体6-甲基-2,4-二氨基-5-(N-(4-甲基苯基)丙基)氨基嘧啶(5b-3)具有最优的二氢叶酸还原酶抑制活性.总结了化合物的构效关系,并用计算机模拟进行了阐释.     

Synthesis and characterization of new unsymmetrical β-diketiminate tris(dimethylamido)hafnium(IV) complexes as potential precursors for the MOCVD of HfO2

The synthesis and characterization of four new unsymmetrical β-diketiminate tris(dimethylamido)hafnium(IV) complexes, [2-(2,6-diisopropylphenyl)amino-4-(phenyl)imino-2-pentene]tris(dimethylamido)hafnium(IV) (5a), [2-(2,6-diisopropylphenyl)amino-4-(4-methylphenyl)imino-2-pentene]tris(dimethylamido)hafnium(IV) (5b), [2-(2,6-diisopropyl-phenyl)amino-4-(4-methoxyphenyl)imino-2-pentene]tris(dimethylamido)hafnium(IV) (5c), and [2-(2,6-diisopropylphenyl)amino-4-(4-chlorophenyl)imino-2-pentene]tris(dimethylamido)hafnium(IV) (5d), are described. Amine elimination reactions work well for introducing unsymmetrical β-diketiminates2-(2,6-diisopropylphenyl)amino-4-(phenyl)imino-2-pentene (4a), 2-(2,6-diisopropylphenyl)amino-4-(4-methylphenyl)imino-2-pentene (4b), 2-(2,6-diisopropylphenyl)amino-4-(4-methoxyphenyl)imino-2-pentene (4c), and 2-(2,6-diisopropylphenyl)amino-4-(4-chlorophenyl)imino-2-pentene (4d) to the tetrakis(dimethylamino)hafnium centre. We discuss the synthetic procedures and characterization using ¹H NMR, ¹³C NMR, IR, mass spectroscopy, and elemental analysis. According to the IR and NMR spectra, unsymmetrical β-diketiminate ligands are bidentate, coordinating through two nitrogens to hafnium.     

Synthesis, IR spectra, crystal structure and DFT studies on 1-acetyl-3-(4-chlorophenyl)-5-(4-methylphenyl)-2-pyrazoline

1-Acetyl-3-(4-chlorophenyl)-5-(4-methylphenyl)-2-pyrazoline has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction. Density functional (DFT) calculations have been carried out for the title compound by using the B3LYP method at the 6-311G** basis set level. The calculated results show that the predicted geometry can reproduce well the structural parameters. Predicted vibrational frequencies have been assigned and compared with experimental IR spectra and they are supported each other. On the basis of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between C(0)(p, m), S(0)(m), H(0)(m) and temperatures.     

A monovacant heteropolytungstate thioderivative: Synthesis and characterization of [(PW11O39)2(H4Mo4S4O6)](10-) and related isomers

[(PW(11)O(39))(2)(Mo(4)S(4)O(4)(OH(2))(2))](10-) anions were obtained through the stereospecific addition of the [Mo(2)S(2)O(2)](2+) oxothiocation to the monovacant alpha-[PW(11)O(39)](7-) anion. K(10)[(PW(11)O(39))(2)(Mo(4)S(4)O(4)(OH(2))(2))].25H(2)O has been isolated as crystals and characterized by X-ray diffraction. The structure revealed a "sandwich-like" dimer of two alpha-[PW(11)O(39)](7-) subunits assembled by the noteworthy central cluster [H(4)Mo(4)S(4)O(6)]. The crystallization of the crude product produces an isomerically pure compound, which was characterized by (31)P and (183)W NMR. IR data were also supplied. In solution, the compound isomerizes, giving a second diastereoisomer. A kinetic experiment, carried out by (31)P NMR, allowed the conditions of the thermodynamic equilibrium to be determined. A structural relationship between the two isomers is proposed, fully consistent with NMR data. Cisoid and transoid isomers result in the relative disposition of each [PW(11)O(39)](7-) subunit, either staggered or eclipsed. An investigation of the formation of the [Mo(2)O(2)S(2)](2+) unit from the polycondensed cyclic precursor [Mo(10)S(10)O(10)(OH)(10)(H(2)O)(5)] and the aggregation process resulting in the oxothio [(PW(11)O(39))(2)(Mo(4)S(4)O(4)(OH(2))(2))](10-) compound has been undertaken. The studies were monitored by (31)P NMR and UV-vis spectroscopies. The reaction is quantitative in nearly stoichiometric conditions.     

2个含呫吨结构双酚化合物的合成

以呫吨酮为原料,经二氯亚砜氯化得到9,9-二氯呫吨中间体,无需分离纯化,将其分别与邻甲酚和2,6-二甲基苯酚进行取代反应,制得2个含呫吨结构的双酚化合物9,9-二(4-羟基-3-甲基苯基)呫吨和9,9-二(4-羟基-3,5-二甲基苯基) 呫吨,产率分别为81.0%和80.5%。 用FTIR、1H NMR、13C NMR和元素分析对其组成和结构进行了表征。 该法具有操作简单、反应条件温和及收率高等优点。