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121.
James P. Donahue 《合成通讯》2013,43(23):3461-3471
The crystal structures of cis‐3‐iodoacrylic acid (1), trans‐3‐iodoacrylic acid (2), trans‐3‐iodoacrylic acid methyl ester (3), 3,3‐diiodopropanoic acid (4), and trans‐2,3‐diiodoacrylic acid (5) are reported. Compounds 1 and 2 are the kinetic and thermodynamic products, respectively, of the hydroiodination of propiolic acid. Compound 4 results from addition of a second equivalent of hydroiodic acid to 1 or 2, whereas 5 results from the addition of trace elemental iodine to propiolic acid. 相似文献
122.
Diego da S. Padilha Adailton J. Bortoluzzi Marciela Scarpellini 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(1):17-22
A novel Ni2+ complex with the N4‐donor tripodal ligand bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl][2‐(pyridin‐2‐yl)ethyl]amine (L), namely, aqua{bis[(1‐methyl‐1H‐imidazol‐2‐yl‐κN3)methyl][2‐(pyridin‐2‐yl‐κN)ethyl]amine‐κN}chloridonickel(II) perchlorate, [NiCl(C17H22N6)(H2O)]ClO4 or [NiCl(H2O)(L)Cl]ClO4 ( 1 ), was synthesized and characterized by spectroscopic and spectrometric methods. The crystal structure of 1 reveals an interesting and unusual cocrystallization of isomeric complexes, which are crystallographically disordered with partial occupancy of the labile cis aqua and chloride ligands. The Ni2+ centre exhibits a distorted octahedral environment, with similar bond lengths for the two Ni—N(imidazole) bonds. The bond length increases for Ni—N(pyridine) and Ni—N(amine), which is in agreement with literature examples. The bond lengths of the disordered labile sites are also in the expected range and the Ni—Cl and Ni—O bond lengths are comparable with similar compounds. The electronic, redox and solution stability behaviour of 1 were also evaluated, and the data obtained suggest the maintenance of structural integrity, with no sign of demetalation or decomposition under the studied conditions. 相似文献
123.
Dr. Sergi Vela Prof. Clémence Corminboeuf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(64):14724-14729
Azoheteroarenes are the most recent derivatives targeted to further improve the properties of azo-based photoswitches. Their light-induced mechanism for trans–cis isomerization is assumed to be very similar to that of the parent azobenzene. As such, they inherited the controversy about the dominant isomerization pathway (rotation vs. inversion) depending on the excited state (nπ* vs. ππ*). Although the controversy seems settled in azobenzene, the extent to which the same conclusions apply to the more structurally diverse family of azoheteroarenes is unclear. Here, by means of non-adiabatic molecular dynamics, the photoisomerization mechanism of three prototypical phenyl-azoheteroarenes with increasing push–pull character is unraveled. The evolution of the rotational and inversion conical intersection energies, the preferred pathway, and the associated kinetics upon both nπ* and ππ* excitations can be linked directly with the push–pull substitution effects. Overall, the working conditions of this family of azo-dyes is clarified and a possibility to exploit push–pull substituents to tune their photoisomerization mechanism is identified, with potential impact on their quantum yield. 相似文献
124.
The formation of four differently protected 4‐deoxy‐D‐lyxo‐hexose derivatives 7, 8, 12, and 14 is described. In the first procedure, a nucleophilic displacement of the allylic mesylate 4 by hydride was combined with a highly stereoselective osmylation of olefin 6 to afford diol 7. In the second radical procedure, tributyl tin hydride was substituted by the cheap and environmentally friendly hypophosphorous acid as a hydrogen donor in the reduction of xanthate 13 to 4‐deoxy lyxo‐hexose 14. 相似文献
125.
Nigel J. Sweeney James Claffey Helge Müller‐Bunz Clara Pampillón Katja Strohfeldt Matthias Tacke 《应用有机金属化学》2007,21(2):57-65
Using 6‐benzo[1,3]dioxolefulvene ( 1a ), a series of benzodioxole substituted titanocenes was synthesized. The benzyl‐substituted titanocene bis[(benzo[1,3]dioxole)‐5‐methylcyclopentadienyl] titanium (IV) dichloride ( 2a ) was synthesized from the reaction of Super Hydride with 1a . An X‐ray determined crystal structure was obtained for 2a . The ansa‐titanocene {1,2‐di(cyclopentadienyl)‐1,2‐di‐(benzo[1,3]dioxole)‐ethanediyl} titanium(IV) dichloride ( 2b ) was synthesized by reductive dimerisation of 1a with titanium dichloride. The diarylmethyl substituted titanocene bis(di‐(benzo[1,3]dioxole)‐5‐methylcyclopentadienyl) titanium(IV) dichloride ( 2c ) was synthesized by reacting 1a with the para‐lithiated benzodioxole followed by transmetallation with titanium tetrachloride. When titanocenes 2a–c were tested against pig kidney (LLC‐PK) cells inhibitory concentrations (IC50) of 2.8 × 10?4, 1.6 × 10?4 and 7.6 × 10?5 M , respectively, were observed. These values represent improved cytotoxicity against LLC‐PK, when compared with unsubstituted titanocene dichloride, but are not as impressive as values obtained for titanocenes previously synthesized using the above methods. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
126.
Kiyoshi Endo Takahiro Kitagawa Kenji Nakatani 《Journal of polymer science. Part A, Polymer chemistry》2006,44(13):4088-4094
The effect of an alkyl substituted in the aromatic ring of the salen ligand on the polymerization of butadiene (Bd) with (salen)Co(II) complexes in combination with methylaluminoxane (MAO) was investigated. The activity for the polymerization of Bd was influenced significantly by the introduction of alkyl groups at the 3,3′,5,5′‐positions in the aromatic ring of the salen ligand, and both the polymerization rate and 1,4‐cis contents increased in the following order with respect to the alkyl group: H < CH3 < t‐C4H9. This is in good agreement with the bulkiness of the alkyl groups. The activity for the polymerization of the (salen)Co(II) complex possessing t‐C4H9 at the 3,3′‐positions was higher than that of the (salen)Co(II) bearing t‐C4H9 at the 5,5′‐positions. Thus, the introduction of bulky substituents at the 3,3′‐positions of the salen ligand was an important factor in achieving both high activity and high 1,4‐cis selectivity in the polymerization of Bd with (salen)Co(II) complexes in combination with MAO. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4088–4094, 2006 相似文献
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129.
The synthesis of a C-6 hydroxy tricyclic sulfone was described with two key reactions: the Suzuki coupling and the regioselective and stereoselective cis ring opening of the epoxide. Overall, the 14-step synthesis was achieved in 2.1% yield. 相似文献
130.
A series of new dihydropyridines, butanamide, dihydropyridazines and thiourea derivatives have been prepared through the reactions of 3‐aminopyridine ( 1 ) and N‐(pyridin‐3‐yl)‐3‐(pyridin‐3‐ylimino)butanamide 3 with some electrophilic reagents, aryl diazonium salts and isothiocyanates. Elementary analysis, MS, IR, and 1H NMR spectra confirmed the identity of the products. 相似文献