Synthesis and structure of some substituted 2-amino-4-aryl-7-propargyloxy-4H-chromene-3-carbonitriles

A series of 2-amino-7-hydroxy-4H-chromene-3-carbonitriles 4a–l were synthesized through three-component reaction using sodium carbonate as a catalyst. The reaction was carried out in 96% ethanol-water medium (1:20 ratio in volume). Propargyl ether compounds 5a–l of these chromene-3-carbonitriles were successfully synthesized from corresponding hydroxyl chromene derivatives by reaction with propargyl bromide. Two different procedures were applied in this process: the procedure that used potassium carbonate in dried acetone and the procedure that used sodium hydride in dried DMF. The latter gave the ethers 5a–l in higher yields. The single-crystal X-ray structure of propargyl ether 5g has been recorded.     

4-取代-2-甲基-6,7-亚甲二氧基-3-喹啉酸乙酯的合成及表征

喹啉及其衍生物是合成抗疟药物和某些金属萃取剂的重要原料[1,2]。文献[3,4]曾报道2,3 二取代喹啉衍生物的合成方法。本文以1,2 亚甲二氧基苯为原料,通过酰化、硝化、还原和催化缩合,得到四种4 取代 2 甲基 6,7 亚甲二氧基 3 喹啉酸乙酯Ⅳ,产率为74～87%。化合物Ⅳa-Ⅳd分别通过IR、1HNMR谱、元素分析和质谱表征。合成路线如图1所示。R=a,CH3;b,C2H5;c,CH2CH2CH3;d,CH(CH3)2。图1　4 取代 2 甲基 6,7 亚甲二氧基 3 喹啉酸乙酯合成路线Fig.1　Syntheticroutenof4 substitrtedethyl 2 methyl 6,7 methylenedioxy 3 quinolinecar…     

Modified procedure for the synthesis of 2-chloroquinoline-3-carbaldehydes using phosphorus pentachloride

An alternative, convenient, and efficient procedure for the synthesis of 2-chloroquinoline-3-carbaldehyde was carried out by the action of Vilsmeier’s reagent on acetanilides using phosphorus pentachloride as chlorinating agent in place of phosphoryl chloride, obtaining good yields for activated acetanilides. The optimal conditions for this reaction requires only 4.5 equivalents of phosphorus pentachloride, 3 equivalents of N,N-dimethylformamide, and 1 equivalent of the corresponding acetanilide at 100 °C for approximately 4 h.     

Synthesis and characterization of a novel and green rod-like magnetic ZnS/CuFe2O4/agar organometallic hybrid catalyst for the synthesis of biologically-active 2-amino-tetrahydro-4H-chromene-3-carbonitrile derivatives

The magnetic biocompatible rod-like ZnS/CuFe₂O₄/agar organometallic hybrid catalyst was designed and prepared based on a natural macromolecule (agar) through a green and convenient method using inexpensive, nontoxic, and easily available substances. Then, the as-prepared catalyst was characterized by several techniques such as Fourier transform-infrared spectroscopy, energy-dispersive X-ray analysis, scanning electron microscopy image, transmission electron microscopy, vibrating sample magnetometry curve, X-ray diffraction pattern, and thermogravimetric analysis. Eventually, the catalytic application of the ZnS/CuFe₂O₄/agar nanobiocomposite was assessed in sequential Knoevenagel condensation–Michael addition reaction of dimedone, malononitrile, and different substituted aromatic aldehydes for the synthesis of 2-amino-tetrahydro-4H-chromene-3-carbonitrile derivatives. Some notable strengths of this environmentally benign catalyst include simplicity of catalyst preparation and separation, affording desired products with satisfactory yields (81%–97%) in very short reaction times (3–18 min), and with no need for complicated work-up processes. Experimental tests showed that the catalyst can be successfully reused after five sequential runs without significant reduction in its catalytic efficiency.     

Expedient Strategy for the Synthesis of 5-Acylethynylpyrrole-2-carbaldehydes

5-Acylethynylpyrrole-2-carbaldehydes have been synthesized from the protected pyrrole-2-carbaldehydes by their transition-metal-free topochemical mechanoactivated ethynylation with acylbromoacetylenes in a solid Al₂O₃ medium (room temperature, 6 h, 41–54% yields).     

Directed synthesis of semicarbazones,thiosemicarbazones, and guanylhydrazones of 1-vinylpyrrole-2-carbaldehydes

Previously unknown 1-vinylpyrrole semicarbazones, thiosemicarbazones, and guanylhydrazones have been obtained in 68.0–90.5% yield by the reaction of 1-vinylpyrrole-2-carbaldehydes with semicarbazide, thiosemicarbazide, and aminoguanidine. Dedicated to Academician B. A. Trofimov on his 70^th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1384–1390, September, 2008.     

Investigation of amination in 4-chloro-2-phenylquinoline derivatives with amide solvents

Novel 4-amino-2-phenylquinoline derivatives were synthesized by reacting various 4-chloro-2-arylquinoline compounds having activated chloro group with the corresponding amide solvents at reflux for overnight. The activity of amination by the amide solvents depended on the competition between the steric and electronic effect of the N-substituents on the amino group. Their activities were shown as N,N-dimethylformamide>N,N-diethylformamide>N-methylformamide>formamide>N,N-dimethylacetamide>N,N-dimethylpropionamide. The yields for the amination products seemed proportional to the ease of the dissociation of the amides.     

The isolation and synthesis of 3-chloro-4-hydroxyphenylacetamide produced by a plant-associated microfungus of the genus Xylaria

Chemical investigations of the fermentation broth from the microfungus Xylaria sp. have afforded the new natural product 3-chloro-4-hydroxyphenylacetamide 1 and the previously reported fungal metabolite 3-chloro-4-hydroxyphenylacetic acid 2. This letter reports the isolation and full spectroscopic characterisation of compounds 1 and 2 by NMR, UV, IR and MS data. The crystal structure and one-pot synthesis of 3-chloro-4-hydroxyphenylacetamide are also reported.     

A new approach to the facile synthesis of 2-substituted-quinazolin-4(3H)-ones

A new approach to the facile synthesis of 2-substituted-quinazolin-4(3H)-ones and its derivatives using the condensation reaction of substituted 2-aminobenzamide and orthoesters is reported.     

A re-investigation of the Fries rearrangement of 3-chlorophenyl acetate and synthesis of 2-azido-1-(4-(benzyloxy)-2-chlorophenyl)ethanone from 4-bromo-3-chlorophenol

The Fries rearrangement of 3-chlorophenyl acetate provided the expected 4-chloro-2-hydroxy-acetophenone as the major product and 2,4-diacetyl resorcinol and 2-chloro-4-hydroxy-acetophenone as minor products. 4-Benzyloxy-2-chloroacetophenone was prepared by a Heck reaction and then elaborated to 4-benzyloxy-2-chlorophenacyl azide.     

Novel synthesis of 2-butyl-5-chloro-3H-imidazole-4-carbaldehyde： A key intermediate of Losartan

A novel method for synthesis of 2-butyl-5-chloro-3H-imidazole-4-carbaldehyde 2, a key intermediate of Losartan was reported. The compound 2 was synthesized from starting material dimethyl malonate 6 and n-valeronitrile 8 by six steps with an overall yield of 40%.The key step including the reaction of compound $ with POCI3/DMF followed by hydrolysis to give compound 2 with the yield of 68%.     

Breathing air as oxidant: Optimization of 2-chloro-2-oxo-1,3,2-dioxaphospholane synthesis as a precursor for phosphoryl choline derivatives and cyclic phosphate monomers

Phosphoryl choline derivatives are important compounds for drug development. Also other phosphoesters have received increased demand in recent years. Many of such compounds rely 2-chloro-2-oxo-1,3,2-dioxaphospholane (COP) as an intermediate. COP is available in a two-step reaction from the cyclic adduct of phosphorus chloride and ethylene glycol after oxidation. Although commercially available, in-house synthesis of COP is often required due to pricing, purity, and delivery issues. Air is a convenient and economical oxidizing agent, yet not used for synthesis of COP. While slow consumption of the P(III)-precursor 2-chloro-1,3,2-dioxaphospholane with molecular oxygen from a gas bottle, high amounts of unreacted oxygen are lavished and even may cause an explosion. Oxygen from air is a reasonable and safer alternative. Additionally, catalytic amounts of cobalt(II)chloride increase the reaction kinetics remarkably. The results presented allow a controlled and fast access to a variety of phosphoesters by optimized reaction conditions of COP and its derivatives.     

A facile and efficient approach for the synthesis of 3-arylthiazol-2(3H)-one

A facile and efficient method for synthesis of 3-arylthiazol-2(3H)-one through the reaction of acyl azide and 1,4-dithiane-2,5-diol was reported. This reaction proceeded at 80?°C at first and then in acidic condition at room temperature, to afford products in good yields for a wide range of substrates and a possible mechanism has also been proposed.     

Asymmetric synthesis of L-carnitine from (R)-3-chloro-1,2-propanediol

A practical chemical synthesis of L-carmtine(1) has been accomplished from(R)-3-chloro-1,2-propanediol((R)-4),which is a main by-product originated from(R,R)-Salen Co(Ⅲ) catalyzed hydrolytic kinetic resolution(HKR) of(±)-epichlorohydrin.(R)-4 was utilized as a chiral starting material to prepare the key intermediate cyclic sulfite((R)-S).The new synthetic approach demonstrated an efficient utilization of organic by-product for the asymmetric synthesis of bioactive compounds.     

Domino Vilsmeier-Haack/ring closure sequences: a facile synthesis of 3-chlorobenzo[b]thiophene-2-carbaldehydes

Vilsmeier’s reagent treatment of substituted diphenacyl sulfides or diphenacyl disulfides has led to the formation of a series of benzfused 3-chlorothiophene-2-carbaldehydes by a Domino Vilsmeier-Haack reaction/ring closure sequence, opening a new route for the synthesis of 3-chlorobenzo[b]thiophene-2-carbaldehydes and their benzfused analogues. A plausible mechanism has been proposed.     

Photoreaction of 2′-chloro-4-R-benzanilide: synthesis of 2-(4-R-phenyl)-1,3-benzoxazole and 9-R-phenanthridin-6(5H)-one (R=H, CH3, CH3O)

The UV photolysis of 2′-chloro-4-R-benzanilides in acetonitrile solution under nitrogen atmosphere leads to the formation of intramolecular photocyclization products (9-R-phenanthridin-6(5)-one, 20–30%), along with the minor photoreduction, photo-Fries, and intramolecular photosubstitution products. The photoreaction of 2′-chloro-4-R-benzanilide in acetonitrile solution containing 10% of water or aqueous sodium hydroxide however gives 2-(4-R-phenyl)-1,3-benzoxazole as a major product (30%) along with the photoreduction, photo-Fries and intramolecular photocyclization products.     

A facile synthesis of novel unsymmetrical N-(4-oxo-2-phenyl-3(4H)-quinazolinoyl)-N-(aryl)acetamidines

<正>A series of novel unsymmetrical N-(4-oxo-2-phenyl-3(4H)-quinazolinoyl)-N-(aryl) acetamidines was synthesized by reacting ethyl(1H)-N-(4-oxo-2-phenylquinazolin-3(4H)-y1)ethanimidoate(2) and suitable reactive aromatic amines.Structures' determination of the synthesized compounds was carried out using spectroscopic techniques including IR,~1H NMR,and mass spectrometry. Structural effects on reactivity were also studied.     

Heterogeneous catalytic ozonation process for removal of 4-chloro-2-nitrophenol from aqueous solutions

This research investigated the efficiency of nanosized ZnO in the catalytic ozonation of 4-chloro-2-nitrophenol and determined the effect of pH on heterogeneous catalytic ozonation. Use of ozone with ZnO catalyst leads to conversion of 98.7% of 4-chloro-2-nitrophenol during 5 min. In addition, it was found that in ZnO catalytic ozonation, the degradation efficiency of 4-chloro-2-nitrophenol was higher at low pH conditions (pH 3.0) than high pH (pH 7–9). This result was not in accordance with ozonation alone, following which higher pH had positive effect on the degradation of 4-chloro-2-nitrophenol. During the catalytic ozonation of 4-chloro-2-nitrophenol, an increase of nitrate ions in water sample solution was observed. At pH = 3, the concentration of nitrate formed during nano-ZnO catalytic ozonation was 7.08 mg L⁻¹ and the amount of total organic carbon was 54.9% after 30 min.     

Vibrational assignment of the spectral data and thermodynamic properties of 2-chloro-4-fluorobenzophenone using DFT quantum chemical calculations

The FT-Raman (3500-100 cm⁻¹) and FT-IR (4000-450 cm⁻¹) spectra of 2-chloro-4-fluorobenzophenone were recorded in the solid phase. Density functional theory calculations with B3LYP/6-31G (d, p) basis set was used to determine the ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities and Raman activities of this compound. Potential energy distributions (PEDs) and normal modes, for the spectral data computed at B3LYP/6-31G (d, p) level, have also been obtained from force-field calculations. The wavenumbers found after scaling of the force field showed very good agreement with the experimentally determined values. A comparison of the theoretical spectra and experimental FT-IR and FT-Raman spectra of the title molecule has been made and full vibrational assignments of the observed spectra have been proposed. On the basis of vibrational analyses, the thermodynamic properties of title compound at different temperatures have been calculated.