共查询到20条相似文献,搜索用时 421 毫秒
1.
Justyna ?aweckaZbigniew Karczmarzyk Ewa WolińskaEwa Olender Danuta BranowskaAndrzej Rykowski 《Tetrahedron》2011,67(17):3098-3104
The synthesis of conformationally strained 2,2′-bipyridine thiamacrocycles 5, 6, 9, 10 and their chiral sulfoxides 11-14 is elaborated using, (1) homo-coupling of 1,2,4-triazine sulfide 3 with potassium cyanide and (2) Diels-Alder/retro Diels-Alder (DA-rDA) with 2,5-norbornadiene or 1-pyrrolidino-1-cyclopentene as the key steps. The crystal structure determinations of 4-6 and the theoretical calculations at DFT/B3LYP/6-311G∗∗ level were conducted thus establishing conformational preferences of the target thiamacrocycles 相似文献
2.
Pilar Cabildo Concepción López Marta Pérez-Torralba M. Rosario Torres José Elguero 《Journal of Molecular Structure》2011,985(1):75-81
3-Bromo-1-methyl-7-nitro-1H-indazole (1), 3-bromo-2-methyl-7-nitro-2H-indazole (2) and 3,7-dinitro-1(2)H-indazole (3) have been synthesized and characterized by X-ray diffraction, 13C and 15N NMR spectroscopy in solution and in solid-state. The dihedral angles obtained in the crystal structures are in good agreement with the molecular parameters calculated using DFT B3LYP calculations employing the 6-311++G(d,p) basis set. Compounds 1 and 2 present intermolecular halogen bonds between the bromine and the oxygen atoms of the nitro group and in compound 3 inter- and intramolecular hydrogen bonding exists. 相似文献
3.
Phytochemical investigations on the organic extracts of the leaves of Suregada multiflora have led to the isolation of ten tetracyclic diterpene lactones 1-10, members of a rare class of abiatene diterpene lactones. Compounds 1-5 were found to be new. The structures of gelomulides F (11), D (12) and E (13) were revised on the basis of 2D NMR and X-ray diffraction evidences. Compounds 1 and 2 contain an epoxy linkage between C-8 and C-14, whereas compounds 3-5 were identified as 8,14-dihydroxy analogues of diterpene lactones. The stereochemical assignments in new compound 1 are based on X-ray diffraction analysis. Compounds 6 and 7 were identified as the known gelomulides A, G. The structures of compounds 7-9 were unambiguously confirmed by X-ray diffraction analyses. 相似文献
4.
The geometry and energy profiles of the mutarotation pathway present in the equilibrium of 6-deoxy-β-l-mannopyranosyl 2,4-dinitrophenylhydrazine (1a), 6-deoxy-l-mannose 2,4-dinitrophenylhydrazone (1b), and 6-deoxy-α-l-mannopyranosyl 2,4-dinitrophenylhydrazine (1c) were modeled by DFT calculations at B3LYP/6-31G(d) level affording ΔGDFT=0.000 kcal/mol, ΔGDFT=0.174 kcal/mol, and ΔGDFT=3.411 kcal/mol, respectively. Experimentally, the β-l-pyranose 1a occurs in 50% followed by the acyclic structure 1b in 44% as well as by the α-l-anomer 1c in 6%. The conformations of 1a-c and their corresponding 2,3,4-triacetyl derivatives 2a-c were studied by molecular modeling and NMR spectroscopy. IR frequencies, NMR chemical shifts, and X-ray diffraction analysis were employed to compare theoretical with experimental structural parameters. 相似文献
5.
《Tetrahedron》2011,67(50):9729-9735
[3+2] Cycloadditions of (1Z,4R∗,5R∗)-1-arylmethylidene-4-benzoylamino-3-oxo-5-phenylpyrazolidin-1-ium-2-ides 1a-e to methyl methacrylate gave the 1-CO2Me regioisomers 3/3′, exclusively, in 1-67% yields. Stereocontrol was dependent on the ortho-substituents at the 1′-aryl group in dipole 1: ortho-unsubstituted dipoles 1a-c gave the major (1R∗,3R∗,5R∗,6R∗)-isomers 3a-c, whilst ortho-disubstituted dipoles gave the major (1R∗,3S∗,5R∗,6R∗)-isomers 3′d,e. The structures of cycloadducts were determined by NMR and X-ray diffraction. 相似文献
6.
G. Brancatelli 《Journal of organometallic chemistry》2007,692(25):5598-5604
The [Pd(N-N∗)Cl2] complexes have been obtained, as yellow solids, in almost quantitative yields; N-N∗ indicate bidentate chiral ligands (Sa)-1, (Sa)-2, (S,S)-3, (R,R)-4, containing the rigid 2-pyridinyl or 8-quinolinyl building block skeleton and the C2-symmetric chiral framework trans-2,5-dimethylpyrrolidinyl or (S)-(+)-2,2′-(2-azapropane-1,3-diyl)-1,1′-binaphthalene. The ligands pairs have the same C2-symmetric chiral framework but different building block skeleton, beyond that for the basicity in the N-donor atoms, for rigidity and flexibility features. The N-N∗ ligands act as chelating ligands leading a square planar geometry. The compounds [Pd(S,S-3)Cl2] and [Pd(R,R-4)Cl2] have been also characterised by X-ray diffraction. The rigidity and flexibility features of (S,S)-3 and (R,R)-4 ligands induce a different orientation of the trans-2,5-dimethylpyrrolidinyl moiety with respect to the pyridinyl and quinolinyl plane. This work shows that intrinsic rigidity and flexibility are not enough to define the ligand properties and to preview the effects that they induce on the reactivity of the metal complex. 相似文献
7.
Various mono Cp∗ type titanium mononuclear complexes (1-5) and dinuclear complexes (6 and 7) containing non-Cp type chelate ligand, picolinate group, which has multi-binding sites of N and O atoms were synthesized and fully characterized by 1H and 13C NMR spectroscopy, mass spectroscopy, elemental analysis, and X-ray diffraction study. The 1 and 2/MMAO catalytic systems for ethylene polymerization exhibited a moderate activity and gave the polyethylenes with broad molecular weight distributions. 相似文献
8.
Tomasz Gubica Łukasz Szeleszczuk Dariusz M. Pisklak Dorota K. Stępień Michał K. Cyrański Marianna Kańska 《Tetrahedron》2014
In this paper the comparative structural analysis of a series of compounds (methyl α-d-glucopyranoside, methyl 4,6-O-ethylidene-α-d-glucopyranoside (2), methyl 2,3-di-O-nitro-4,6-O-ethylidene-α-d-glucopyranoside and methyl 3-O-nitro-4,6-O-ethylidene-α-d-glucopyranoside) by way of synthesis leading to methyl 3-O-nitro-α-d-glucopyranoside (5) is reported. The title compound (5) is a novel d-glucosidic mononitrate having potential biological activity against cardiovascular diseases. The structural analysis was supported by single-crystal X-ray diffraction (XRD), 13C CP/MAS NMR spectroscopy and DFT calculations. In the case of 2 and 5, XRD analysis could not be performed due to the fact that 2 is highly hygroscopic and 5 forms improper crystals. However, the molecular structures of 2 and 5 were obtained on the basis of experimental (existing XRD data for similar compounds) and theoretical (DFT optimization) approaches. This showed of very good agreement with the 13C CP/MAS NMR spectral data. 相似文献
9.
Matthias HeydenreichAndreas Koch László LázárIstván Szatmári Reijo SillanpääErich Kleinpeter Ferenc Fülöp 《Tetrahedron》2003,59(11):1951-1959
Starting from the 1′- or 2′-phenyl-substituted 1-(2′-hydroxyethyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline diastereomers 3 and 6, 4-unsubstituted and 4-(p-nitrophenyl)- and 4-oxo-substituted 1-phenyl- and 2-phenyl-9,10-dimethoxy-2H,4H-1,6,7,11b-tetrahydro-1,3-oxazino[4,3-a]isoquinolines (7-12) were prepared. The relative configurations and the predominant conformations of the products were determined by NMR spectroscopy, by quantum chemical calculations and, for (2R∗,4S∗,11bR∗)-9,10-dimethoxy-4-(p-nitrophenyl)-2-phenyl-2H,4H-1,6,7,11b-tetrahydro-1,3-oxazino[4,3-a]isoquinoline (11), by X-ray diffraction. 相似文献
10.
Emerson MeyerAntonio C Joussef Hugo Gallardo Adailton J BortoluzziRicardo L Longo 《Tetrahedron》2003,59(51):10187-10193
Intramolecular nonbonded interactions have been observed in the crystalline structures of 6-ethoxy-2-trifluoroacetyliminobenzothiazoline (4) (S?O close contact) and 6-ethoxy-2-trifluorothioacetyliminobenzothiazoline (5) (S?S close contact). Density functional B3LYP/6-311G∗∗ calculations were performed for all conformers and tautomers of 4 and 5 in order to explain the preference for the S?O and S?S close contact structures. The calculations agree with the observed crystallographic structures only when solvent effects are included via a continuum model, thus showing the importance of the solvent effects to establish the correct relative energies. 相似文献
11.
Lidija Pezdirc 《Tetrahedron letters》2007,48(30):5205-5208
Treatment of (1Z,4R∗,5R∗)-1-arylmethylidene-4-benzamido-5-phenylpyrazolidin-3-one 1-azomethine imines 4a-d with potassium cyanide in the presence of acetic acid resulted in addition of HCN to the exocyclic CN double bond followed by β-eliminative N-N single bond cleavage (ring opening) to give the N-[(1R∗,2R∗)-3-amino-2-benzamido-3-oxo-1-phenylpropyl]benzimidoyl cyanides 6a-d in 28-85% yields. Reaction of dipole 4e with HCN furnished stable intermediate, (1′S∗,4R∗,5R∗)-4-benzamido-1-[cyano(mesityl)methyl]-5-phenylpyrazolidin-3-one (5e), in 76% yield. The structure of compound 6c was determined by X-ray diffraction. 相似文献
12.
Masaru MouriShigeyasu Kuroda Mitsunori OdaRyuta Miyatake Mayumi Kyogoku 《Tetrahedron》2003,59(6):801-811
The azuleno[1,2-a]acenaphthylene (1a) was prepared from 1-pyrrolidinylacenaphthylene (5) and 2H-cyclohepta[b]furan-2-one (6) by the method of the Takase-Yasunami azulene synthesis. Its 1H and 13C NMR spectra indicate that 1a comprises azulene and naphthalene rather than acenaphtylene and heptafulvene in accordance with speculation drawn from a previous study of the DEPE calculations. The solid-state structure of 1a was elucidated by X-ray crystallographical analysis, indicating that 1a is nearly planar and exhibits little bond alternation as seen in the optimized structure at the MB3LYP/6-311G∗ level of theory. All bond lengths observed by the X-ray analysis are in good agreement within 0.024 Å with those calculated. Under pyrolytic conditions 1a underwent azulene-naphthalene rearrangement to give 9 and 10. The electrophilic substitution of 1a was observed at the 7-position and the second reaction at the 3-position. The cycloaddition reaction of 1a with dimethyl acetylenedicarboxylate (DMAD) yielded the 1:1 cycloadduct with a heptalene skeleton 16a and the 1:2 cycloadduct 19, along with the substitution product 17. The X-ray structural analysis of the cycloadducts 16a and 19 is also described. 相似文献
13.
Meg E. Fasulo 《Journal of organometallic chemistry》2011,696(6):1325-1330
The dichloride complex Cp∗(Am)WCl2 (1, Am = [(iPrN)2CMe]−) reacted with the primary silanes PhSiH3, (p-tolyl)SiH3, (3,5-xylyl)SiH3, and (C6F5)SiH3 to produce the W(VI) (silyl)trihydrides Cp∗(Am)W(H)3(SiHPhCl) (2), Cp∗(Am)W(H)3(SiHTolylCl) (3), Cp∗(Am)W(H)3(SiHXylylCl) (4), and Cp∗(Am)W(H)3[SiH(C6F5)Cl] (5). In an analogous manner, 1 reacted with PhSiH2Cl to give Cp∗(Am)W(H)3(SiPhCl2) (6). Complex 6 can alternatively be quantitatively produced from the reaction of 2 with Ph3CCl. NMR spectroscopic studies and X-ray crystallography reveal an interligand H?Si interaction between one W-H and the chlorosilyl group, which is further supported by DFT calculations. 相似文献
14.
Aichen Wang 《Journal of organometallic chemistry》2008,693(16):2679-2682
The reactions of tri(bis(ethyl)amino)phosphorus ylide (Et2N)3PCH2 with cyclopentadienyl (Cp) metal (V) tetrachloride CpMCl4 (M = Nb 1; Ta 3) and pentamethylcycopentadienyl (Cp∗) metal (V) tetrachloride Cp∗MCl4 (M = Nb 2; Ta 4) were investigated. The hexa-coordinate ylide adducts complexes 5 (CpNbCl4(H2CP(NEt2)3)), 6 (Cp∗NbCl4(H2CP(NEt2)3)) and 8 (Cp∗TaCl4(H2CP(NEt2)3)) with pseudo-octahedral geometry were structurally analyzed with X-ray diffraction. Compound 4 (Cp∗TaCl4) reacted with three molar equivalent of phosphorus ylide to form one ionic complex 9 ([H3C-P(NEt2)3][Cp∗TaCl5]) which was also structurally analyzed with X-ray diffraction. The possible formation mechanism of compound 9 has been discussed. 相似文献
15.
Peng-Cheng Zhang 《Journal of organometallic chemistry》2008,693(17):2903-2906
Four half-sandwich cobalt complexes, Cp∗Co(2-PyS)2 (2), Cp∗Co(2-PyS)2 · HI (3), Cp∗Co(2-PyS) (4-PyS) (4), (Cp∗Co)2(μ-PhS)2(μ-2-PyS)I (5) [Cp∗ = pentamethylcyclopentadienyl, 2-PyS = 2-pyridinethiolate, 4-PyS = 4-pyridinethiolate, PhS = benzenethiolate] were successfully synthesized by the reactions of 2-pyridinethione, lithium 4-pyridinethiolate and lithium benzenethiolate with Cp∗Co(2-PyS)I (1), respectively. Complexes 2 and 3 have the structures with two 2-pyridinethiolates ligands coordinated to the cobalt atom. Two different pyridinethiolates ligands can be identified in complex 4. The molecular structure of 5 consists of two Cp∗-Co fragments, which are triply bridged by three sulfur atoms from different ligands. The molecular structures of 3 and 5 were determined by X-ray crystallographic analysis. All the complexes have been well characterized by elemental analysis, NMR and IR spectra. 相似文献
16.
A series of oxovanadium(IV) complexes: TpVO(pzH)(2,4-Cl–C6H3–OCH2COO) (1), TpVO(pzH)(C6H5–OCH2COO) (2), TpVO(pzH)(p-Cl–C6H4–COO) (3), TpVO(pzH)(3,5-NO2–C6H3–COO) (4), Tp∗VO(pzH∗)(p-Cl–C6H4–COO) (5) and Tp∗VO(pzH∗)(p-Cl–C6H4–COO) · CH3OH (6) (Tp = hydrotris(pyrazolyl)borate, pzH = pyrazole, Tp∗ = hydrotris(3,5-dimethylpyrazolyl)borate, pzH∗ = 3,5-dimethylpyrazole) were synthesized and their crystal structures were determined by X-ray diffraction. In all the complexes, the vanadium ions are in a distorted-octahedral environment with a N4O2 donor set. Hydrogen bonding interaction exists in each complex. Complexes 1 and 2 are hydrogen-bonded dimers. Dimeric units of 2 are connected to one another via weak inter-molecular C–H···O interactions to form a 2D network on the bc-face. In 3–6 there exist intramolecular N–H···O hydrogen bonds between the neutral pyrazole/3,5-dimethylpyrazole and the uncoordinated carboxyl oxygen atom. In addition, the catalytic activity of complex 2 in a bromination reaction in phosphate buffer with phenol red as a trap was evaluated by UV–Vis spectroscopy. Furthermore, the elemental analyses, IR spectra and thermal stabilities were recorded. 相似文献
17.
Mousa Al-Noaimi Musa I. El-Barghouthi Obada S. Abdel-RahmanSalim F. Haddad Abdel Monem Rawashdeh 《Polyhedron》2011,30(11):1884-1890
Geometry optimization for a cis-[RuII(dppe)LCl2] (1-8) {L = C6H5NNC(COCH3)NAr, Ar = 2,4,6-trimethylphenyl (L1), 2,5-dimethylphenyl (L2), 4-tolyl (L3), phenyl (L4), 4-methoxyphenyl (L5), 4-chlorophenyl (L6), 4-nitrophenyl (L7), 2,5-dichlorophenyl (L8); dppe = Ph2P(CH2)2PPh2} was effected using the gaussian 03 protocol at density functional theory (DFT) B3LYP level with 6-31G∗/lanl2dz mixed basis. In addition, the complex cis-[RuII(dppe)L3Cl2] (3) has been further characterized by X-ray diffraction analysis. It was found that the optimized structure using 6-31G∗/lanl2dz has a large agreement with the X-ray data. DFT calculations show that upon solvation both Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) molecular orbitals are stabilized and their energy gap is increased. TD-DFT calculations show that the intense broad band centered at λmax ∼ 506 nm is assigned to “mixed metal-ligand-to-ligand charge-transfer” (MMLLCT) while the weak low energy band centered on ∼840 nm is assigned to the pure MLCT transition. The low intensity for the low energy MLCT transition can be explained by the large mixing between the azoimine (L) and (Ru(dπ)) orbital. 相似文献
18.
Karl A. Tupper 《Journal of organometallic chemistry》2005,690(7):1689-1698
The synthesis and characterization of complexes containing a Cp∗Sc(R2bpy) (Cp∗ = pentamethylcyclopentadienyl, bpy = 4,4′-R,R-2,2′-bipyridine, R = H, Me) motif are described. Cp∗ScI2 (1) was prepared from Cp∗Sc(acac)2 (acac = acetylacetonate) and AlI3 (2 equiv) in pentane. Compound 1 reacted with bipyridine and 4,4′-dimethyl-2,2′-bipyridine (dmb) in benzene to yield Cp∗ScI2(bpy) (3) and Cp∗ScI2(dmb) (4), respectively. Compound 3 was reduced by alkali metal reductants such as Na/Hg, NaK2, and K in aromatic solvents to yield [Cp∗ScI(bpy)]2 (5). The chloride analog of 5, [Cp∗ScCl(bpy)]2 (7), was prepared from Cp∗ScCl2 by salt metathesis with Li2(dme)2bpy (6) (dme = dimethoxyethane) in toluene. Compounds 1, 5, and 7 have been structurally characterized. Analysis of the bond distances of the bipyridine ligands in 5 and 7, together with infrared and UV/vis spectroscopic data, suggest that the bipyridine ligands in these molecules exist as radical anions. The bipyridine ligands in 5 and 7 are arranged co-facially and are in close proximity (?3.30 Å), suggesting the presence of a π-π interaction. 相似文献
19.
Sodium borohydride-carbonyl reduction of the novel 3-(2-fluoro-5-nitro) phenyl-4-benzoyl-2-azetidinones 3 and 7 gave quantitatively the stereoisomeric carbinols (4R∗,5S∗)-4 and (4R∗,5R∗)-5. Treatment of the latter with sodium hydride gave the title compounds 8 and 9, respectively, with good overall yield. The rationale of the stereochemical relationships outlined in the sequences 3 (or 7)→4→8 and 3 (or 7)→5→9 is given according to the conformational and keto-enol equilibria of the reactant(s). 相似文献
20.
Yoshimitsu Nagao Takashi Honjo Satoru Goto Motoo Shiro Yoshihisa Sei 《Tetrahedron letters》2004,45(47):8757-8761
The dimeric crystalline structure of acetazolamide 1 and thiadiazolinethione 2 bearing intramolecular nonbonded S?O interactions, in each different hydrogen-bonding manner was clarified by their X-ray crystallographic analysis. Existence of the dimeric structure of 1 and 2 in a MeOH solution could be suggested on the basis of their cold-spray ionization mass spectrometry. The intramolecular nonbonded S?O interaction was precisely recognized in the complex crystalline structures of carbonic anhydrase I inhibitor 1 and stromelysin inhibitors 2-4 with each specific enzyme. The computational evaluation of the possible monomeric seven conformers of 1 and two model compounds 5 and 6 of 2-4 based on DFT calculations defined that the conformer bearing the intramolecular nonbonded S?O interaction is most stable. 相似文献