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391.
Fotie J Kemami Wangun HV Fronczek FR Massawe N Bhattarai BT Rhodus JL Singleton TA Bohle DS 《The Journal of organic chemistry》2012,77(6):2784-2790
The real mechanism of the Skraup-Doebner-Von Miller quinoline synthesis remains controversial and not well understood despite several mechanistic studies reported on the matter. A series of unexpected and unusual 5,6,7,8,9,10-hexahydro-6,6-pentamethylenephenanthridines and 2,3,4,5-tetrahydro-4,4-tetramethylene-1H-cyclopenta[c]quinolines have been obtained through the Skraup-Doebner-Von Miller quinoline synthesis. On the basis of these unexpected results and in agreement with some of the previously reported quinoline syntheses, an alternative mechanistic pathway is proposed for this variant of the reaction. It involves the formation of a Schiff base through a reaction between the ketone and the aniline derivative in the first step, followed by a cycloalkenylation at the ortho-position to the amine functional group of the aniline derivative, and an annulation in the final step to close the quinoline ring, leading to a dihydroquinoline derivative. To the best of our knowledge, this is the first report of such a mechanistic pathway being proposed for any variant of the Skraup-Doebner-Von Miller quinoline synthesis. 相似文献
392.
Stefanelli M Pomarico G Tortora L Nardis S Fronczek FR McCandless GT Smith KM Manowong M Fang Y Chen P Kadish KM Rosa A Ricciardi G Paolesse R 《Inorganic chemistry》2012,51(12):6928-6942
Functionalization of the β-pyrrolic positions of the corrole macrocycle with -NO(2) groups is limited at present to metallocorrolates due to the instability exhibited by corrole free bases under oxidizing conditions. A careful choice of the oxidant can limit the transformation of corroles into decomposition products or isocorrole species, preserving the corrole aromaticity, and thus allowing the insertion of nitro groups onto the corrole framework. Here we report results obtained by reacting 5,10,15-tritolylcorrole (TTCorrH(3)) with the AgNO(2)/NaNO(2) system, to give mono- and dinitrocorrole derivatives when stoichiometry is carefully controlled. Reactions were found to be regioselective, affording the 3-NO(2)TTCorrH(3) and 3,17-(NO(2))(2)TTCorrH(3) isomers as the main products in the case of mono- and disubstitution, in 53 and 20% yields, respectively. In both cases, traces of other mono- and disubstituted isomers were detected, which were structurally characterized by X-ray crystallography. The influence of the β-nitro substituents on the corrole properties is studied in detail by UV-visible, electrochemical, and spectroelectrochemical characterization of these functionalized corroles. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations of the ground and excited state properties of these β-nitrocorrole derivatives also afforded significant information, closely matching the experimental observations. It is found that the β-NO(2) substituents conjugate with the π-aromatic system of the macrocycle, which initiates significant changes in both the spectroscopic and redox properties of the so functionalized corroles. This effect is more pronounced when the nitro group is introduced at the 2-position, because in this case the conjugation is, for steric reasons, more efficient than in the 3-nitro isomer. 相似文献
393.
Yang Y Lowry M Schowalter CM Fakayode SO Escobedo JO Xu X Zhang H Jensen TJ Fronczek FR Warner IM Strongin RM 《Journal of the American Chemical Society》2006,128(43):14081-14092
The synthesis of new benzo[a]- and [b]xanthene dye frameworks is described. A unique benzo[a]xanthene, seminaphtho[a]fluorone (SNAFR-1), is studied in a variety of media. The optimization of solution parameters and excitation wavelengths allows SNAFR-1 to display red, green, and blue emission bands of approximately equal intensities and also to produce white light. Ratiometric red (anion) and green (neutral) emissions are observed upon varying solution pH. A pH-independent violet-blue emission band is due to the addition of nucleophiles to the benzylic carbon of SNAFR-1. 相似文献
394.
Clinton Hunt Brent D. Nelson Elisa G. Harmon Frank R. Fronczek Steven F. Watkins Damon R. Billodeaux George G. Stanley 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):546-548
Bis(μ‐3,11‐diethyl‐6,8‐diphenyl‐3,6,8,11‐tetraphosphatridecane‐κ4P3,P6:P8,P11)dirhodium(I) bis(tetrafluoroborate), [Rh2(C25H40P4)2](BF4)2, is a bimetallic complex containing two binucleating tetra‐tertiary phosphine ligands. The distance between the metal centers is 5.4555 (11) Å, with no metal–metal bond. The Rh—P bond distances range from 2.2483 (14) to 2.3295 (14) Å. The geometry about the RhI atoms is tetrahedrally distorted square planar and the dihedral angle between the two coordination planes is 66.28 (5)°. 相似文献
395.
Tod J. Miller Yanwen Fu Frank R. Fronczek Robert P. Hammer 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):e574-e575
The title compound, C18H19NO4, is the key synthetic intermediate in the preparation of α,α‐dibenzyl‐α‐amino acid (dibenzylglycine, Dbg), the disubstituted homologue of phenylalanine, following the dialkylation of ethyl nitroacetate. The molecule does not have its potential mirror symmetry in the crystal, with the two benzyl groups forming N—C—C—C torsion angles of 60.31 (13) and 79.89 (13)°. 相似文献
396.
Hesham Fahmy Jordan K. Zjawiony Sherief Khalifa Frank R. Fronczek 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):o85-o87
The title molecule, 2(R)‐[(1E,3E,7S,8S,11E,13R)‐13‐hydroxy‐4,8,12‐trimethyl‐7,8‐epoxycyclotetradeca‐1,3,11‐trien‐1‐yl]propane‐1,2‐diol, C20H32O4, is a semi‐synthetic analog of sarcophine, the natural cembranoid of marine origin, isolated from the soft coral Sarcophyton glaucum. The conformation of the 14‐membered ring differs substantially from that of sarcophine. The two OH groups of the propane‐1,2‐diol moiety form an unusual weak intramolecular hydrogen bond with an O⋯O distance of 2.788 (2) Å, and the molecules are linked into double chains by intermolecular hydrogen bonds with O⋯O distances of 2.772 (2) and 2.849 (2) Å. 相似文献
397.
Prabodhika Mallikaratchy Richard E. Norman Frank R. Fronczek Thomas Junk 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(10):o571-o574
All three title compounds, prepared from bis(3,5‐dimethyl‐2‐nitrophenyl)ditellurium, exhibit high degrees of intramolecular Te—O coordination. Their Te—O distances increase in the order C8H8BrNOTe < C8H8BrNO2Te < C8H8Br3NO2Te, with distances of 2.165 (3), 2.306 (1) and 2.423 (6) Å, respectively, indicating that C8H8BrNOTe may be more aptly described as 1‐bromo‐4,6‐dimethyl‐2,1,3‐benzoxatellurazole. 相似文献
398.
Thenahandi Prasanthi Deepthika De Silva Sang Gil Youm Frank R. Fronczek Girija Sahasrabudhe Evgueni E. Nesterov Isiah M. Warner 《Molecules (Basel, Switzerland)》2021,26(21)
Three novel small organic heterocyclic compounds: 2-(1,2-diphenyl)-1H-benzimidazole-7-tert-butylpyrene (compound A), 1,3-di(1,2-diphenyl)-1H-benzimidazole-7-tert-butylpyrene (compound B), and 1,3,6,8-tetra(1,2-diphenyl)-1H-benzimidazolepyrene (compound C) were synthesized and characterized for possible applications as blue OLED emitters. The specific molecular design targeted decreasing intermolecular aggregation and disrupting crystallinity in the solid-state, in order to reduce dye aggregation, and thus obtain efficient pure blue photo- and electroluminescence. Accordingly, the new compounds displayed reasonably high spectral purity in both solution- and solid-states with average CIE coordinates of (0.160 ± 0.005, 0.029 ± 0.009) in solution and (0.152 ± 0.007, 0.126 ± 0.005) in solid-state. These compounds showed a systematic decrease in degree of crystallinity and intermolecular aggregation due to increasing steric hindrance, as revealed using powder X-ray diffraction analysis and spectroscopic studies. An organic light-emitting diode (OLED) prototype fabricated using compound B as the non-doped emissive layer displayed an external quantum efficiency (EQE) of 0.35 (±0.04)% and luminance 100 (±6) cd m−2 at 5.5 V with an essentially pure blue electroluminescence corresponding to CIE coordinates of (0.1482, 0.1300). The highest EQE observed from this OLED prototype was 4.3 (±0.3)% at 3.5 V, and the highest luminance of 290 (±10) cd m−2 at 7.5 V. These values were found comparable to characteristics of the best pure blue OLED devices based on simple fluorescent small-molecule organic chromophores. 相似文献