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961.
Treatment of 4‐arylthio‐3‐hydroxy‐2‐pyrones with acetylenedicarboxylates gave 4‐arylthio‐3‐hydroxyphthalates by the base‐catalyzed Diels–Alder reaction via a decarboxylation in good yields. 相似文献
962.
An efficient and chemoselective method for the Friedel–Crafts acylation of aromatic compounds using P2O5/Al2O3 and carboxylic acids. Both aromatic and aliphatic carboxylic acids reacted easily to afford the corresponding aromatic ketones in good yields. 相似文献
963.
Claudio L. Donnici Elaine Henriques Teixeira Pereira Júlio C. Dias Lopes Liliana Marzorati Blanka Wladislaw 《合成通讯》2013,43(3):342-350
The study on reactivity of several α-substituted α-sulfonyl malonates toward 1,4-diazabicyclo[2.2.2]octane (DABCO) and Bu3N is described. The reactivity with DABCO revealed the possible competition between decarbalkoxylation and unexpected desulfonylation, depending on the α-substituent, because of sterical hindrance around the electrophilic centers (SO2 and CO2R). The derivatives with crowded α-substituents suffer selective desulfonylation, and a novel and efficient desulfonylation method can be proposed. The dependence of the reactivity of α-sulfonyl malonates on the sterical hindrance around the electrophilic centers is confirmed by conformational analysis (Macromodel/MM2? and Mopac/MP3). The carbanionic mechanism is proved because the corresponding protonated, deuterated, and sulfenylated products were obtained by addition of the corresponding electrophilic agents. Bu3N showed itself to be a novel selective decarbalkoxylation agent for any α-substituted α-sulfonyl malonate. 相似文献
964.
Subban Kathiravan 《合成通讯》2013,43(20):3068-3076
Facile synthesis of a series of naphtho[2,1,b]pyrano pyrrolo thiazoles was accomplished in good yields in a one-pot reaction through intramolecular 1,3-dipolar cycloaddition of cyclic azomethine ylides with Baylis–Hillman adducts as dipolarophiles. The protocol is applicable to a wide variety of photochromic and biologically active napthopyrano products. The regio- and stereochemical outcome of the cycloaddition reaction was ascertained by x-ray crystallographic study of one of the cycloadducts. 相似文献
965.
A novel synthetic utility of NaICl2 for the preparation of bis(4-dimethaminophenyl)arylmethanes and bis(4-dimethaminophenyl)alkanes is described. In the presence of an aqueous solution of NaICl2, the reaction of arenes with aromatic aldehydes gives corresponding triarylmethane derivatives regioselectively in moderate to good yields. The method is also useful for the preparation of diarylalkane derivatives by using aliphatic aldehydes. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications ® to view the free supplemental file. 相似文献
966.
A simple wet chemical method is used to prepare zinc oxide nanoflowers (ZnO NFs) which were subjected to various characterization techniques such as XRD, FTIR, UV–Vis, FE-SEM, and XPS. XRD pattern indicates pure, crystalline, and monodispersed form with hexagonal wurtzite phase. The 3-D flower shape morphology with hexagonal ZnO nanorods was confirmed in FE-SEM. The synthesized ZnO NFs was used to study catalytic behavior in Kabachnik–Fields reaction under controlled ultrasound cavitation technique. High surface-to-volume ratio of ZnO NFs and the effect of ultrasonication enhances the yield of α-aminophosphonate. The catalyst was recycled and reused four times without any significant loss of its catalytic activity. Moreover, existing method becomes attractive and practical due to its easy, clean, fast, cost-effective, and eco-friendly procedure. 相似文献
967.
Phosphorylation of phenols with diethyl cyanophosphonate in methylene chloride solution at 0°C is an easy, rapid and good yielding reaction. 相似文献
968.
Two complexes, [Cu2(Htdb)4(H2O)2] (1) and [Cd(bipy)2(Hmcmbc)2] (2) (H2tdb = 2,2-thiodibenzoic acid, H2mcmbc = m-(carboxyl-methyloxy)-benzenecarboxylic acid, bipy = 4,4'-bipyridine), have been prepared, and were characterized by elemental analysis, FT-IR and single-crystal X-ray diffraction. Structures indicate that complex 1 is a single molecule, and 2 is a one-dimensional chain. Their two-and three-dimensional frameworks are constructed through hydrogen bonding, π…π or C–H…π stacking, and such other weak interactions. The cyclic voltametric behavior of complex 1 and luminescence property of complex 2 were investigated. 1 belongs to the triclinic system, space group P with a = 7.8607(6), b = 11.7619(9), c = 15.3481(12) , α = 109.3670(10), β = 92.4420(10), γ = 92.0450(10)°, V = 1335.65(18) 3, Mr = 1256.26, Dc = 1.5619(2) g/cm3, F(000) = 642, μ = 1.029 mm–1, Z = 1, the final R = 0.0289 and wR = 0.0763 for 5199 observed reflections with I > 2σ(I). Complex 2 crystallizes in triclinic, space group P with a = 9.6378(10), b = 9.7508(10), c = 19.055(2) , α = 88.7020(10), β = 80.5260(10), γ = 69.2000(10)o, V = 1649.9(3) 3, Mr = 815.07, Dc = 1.641 g/cm3, μ = 0.732 mm-1, F(000) = 828, Z = 2, the final R = 0.0511 and wR = 0.1149 for 4729 observed reflections (I > 2σ(I)). 相似文献
969.
The standard (po = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, at the reference temperature of 298.15 K, of 2-amino-4-methylpyrimidine ((98.1 ± 1.6) kJ · mol−1), 2-amino-4,6-dimethylpyrimidine ((55.9 ± 1.8) kJ · mol−1) and 4-amino-2,6-dimethylpyrimidine ((60.1 ± 1.8) kJ · mol−1) were calculated from the enthalpies of formation, in the crystalline phase, and enthalpies of sublimation, derived, respectively, from static bomb combustion calorimetry and Knudsen effusion technique results. In order to quantify the resonance effects arising from the substitution on the pyrimidine ring, hypothetical isodesmic reactions were used to analyze the experimental gaseous-phase enthalpies of formation. The aromaticity of benzene, pyridine, pyrimidine and the substituted pyrimidines was investigated in terms of magnetic (NICS), geometric (HOMA), electronic (Shannon aromaticity, QTAIMs ring critical point properties and HOMO–LUMO gap), reactive (hardness), vibrational (Kekulé mode) and spectroscopic (UV–Vis) properties. 相似文献
970.
Preparation of a sulfonated fused-silica capillary and its application in capillary electrophoresis and electrochromatography 总被引:1,自引:0,他引:1
In the present paper, two new methods, sol-gel and chemical bonding methods, were proposed for preparation of sulfonated fused-silica capillaries. In the sol-gel method, a fused-silica capillary was coated with the sol solution obtained by hydrolysis of 3-mercaptopropyltrimethoxysilane (MPTS) and tetramethoxysilane, and followed by age; while in the chemical bonding method, a capillary was chemically bonded directly with MPTS. Then, both the resulting capillaries were oxidized with an aqueous solution of hydrogen peroxide solution (H2O2) (30%, m/m) to obtain the sulfonated capillaries. The electroosmotic flow (EOF) for the sulfonated capillaries was found to remain almost constant within the studied pH range, and greater than that of the uncoated capillary. However, the coating efficiency of the capillary prepared by chemical bonding method was higher than that by sol-gel method, by comparing their magnitude of the EOF, the degree of disguise of the silanol and reproducibility of preparation procedure. The effects of the electrolyte's concentration and the content of methanol (MeOH) on the EOF were also studied. Especially, the study of the apparent pH (pH*) on the EOF in a water-MeOH system was reported. Finally, capillary electrophoretic separation of seven organic acids was achieved within 6.5 min under optimal condition using the chemically bonded sulfonated capillary. Moreover, separation of four alkaloids on the sulfonated capillary was compared with that on uncoated capillary in different conditions. Ion-exchange mechanism was found to play a key role for separation of these four basic analytes on the sulfonated capillary. 相似文献