Highly regioselective synthesis of 1-aryl-3 (or 5)-alkyl/aryl-5 (or 3)-(N-cycloamino)pyrazoles

[Reaction: see text]. An efficient highly regioselective protocol for the synthesis of isomeric 1,3-diaryl (or 1-aryl-3-alkyl) and 1,5-diaryl (or 1-aryl-5-alkyl)-5 (or 3)-(N-cycloamino)pyrazoles has been reported by cyclocondensation of common alpha-oxoketene N,S-acetal precursors with arylhydrazines by variation of reaction conditions.     

Synthesis of 1-aryl-3-(3-pyrrolyl)-5-oxopyrazoles

1-Aryl-3-(2,4-dimethyl-5-ethoxycarbonyl-3-pyrrolyl)-5-oxopyrazoles were obtained by condensation of ethyl -(2,4-dimethyl-5-ethoxycarbonyl-3-pyrrolyl)--ketopropionate with arylhydrazines. Electron-donor substituants in the aromatic ring of the arylhydrazines accelerate the cyclization of the intermediate hydrazones, whereas electron-acceptor substituents hinder cyclization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1076–1081, August, 1983.     

Synthesis of 3-aryl-5-methyl-3-(isoxazolyl)-3-oxopropionate oximes

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1141–1142, August, 1990.     

Structure of 1(5)-aryl-3-phenyl-5(1)-(2-benzothiazolyl)formazanes

1,3-Diphenyl-5-(2-benzothiazolyl)formazane exists in its crystalline state (based on x-ray crystal structure data) in the E ^1,2 Z ^2,3 Z ^3,4-conformation, which is stabilized by intramolecular hydrogen bonding (IMHB); the proton is localized on the nitrogen atom which is bound to the heterocycle. In chloroform solutions 1(5)-aryl-3-phenyl-5(1)-(2-benzothiazolyl)formazanes exist in the form of equilibrium mixtures of their chelate and open E ^1,2 Z ^2,3 Z ^3,4-forms, in which the first of these forms predominates. Based on their ¹³ C-NMR spectral data the tautomeric equilibrium involving these forms is shifted in favor of the benzothiazolylhydrazone form. The amount of tautomer containing the benzothiazolidene fragment structure increases in DMSO solution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1268–1274, September, 1991.     

Structure of 1-aryl-3-alkyl-5-(2-benzothiazolyl)formazans

The isomeric and tautomeric structures of 1-aryl-3-alkyl-5-(2-benzothiazolyl)formazans in solutions were investigated by means of NMR, IR, and electronic spectroscopy. It is shown that the nature of the solvent and the alkyl substituent in the 3 position affects the ratio of the Z and E isomers relative to the C=N bond of the azohydrazone chain. An increase in the length of the alkyl substituent in the 3 position leads to preponderance of the Z isomer in solution, while branching stabilizes the Z configuration with an N²...HN⁵ intramolecular hydrogen bond (IMHB), regardless of the solvent. The nature of the solvent has a significant effect on the ratio of the amino and imino tautomeric forms of the E isomers. The benzothiazolylhydrazone form predominates in CHCl₃, while the tautomer with a benzothiazolidene fragment is the major form in DMSO.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 834–839, June, 1993.     

Reductive transformations of 3-alkyl- and 3-aryl-5-(4-pyridyl)-2-isoxazolines

The reactions of 3-R-(4-pyridyl)-2-isoxazolines and the products of their hydrogenolysis over Raney Ni/AlCl₃ with NaBH₄ and KBH(s-Bu)₃ as the reducing agents were studied. New polyhydroxyprostanoids were synthesized.Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, 220141 Minsk; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 252–258, February, 1999.     

2-芳基-3-N-丙酰基-5-(4-溴苯基)-1,3,4-噁唑啉类化合物的合成

噁唑啉类化合物是重要的杂环族化合物,在农药化学和医药化学中应用及其广泛。在现有的文献中已报道的大多是3-N乙-酰基-1,3,4噁-唑啉类化合物的合成[1-6],而3-N乙-酰基-1,3,4噁-唑啉类化合物的合成却很少见。为了深入研究同一分子中聚集不同骨架杂环化合物的合成以及开发新型高     

3-N-丙酰基-2-芳基-5-(2-碘苯基)-1,3,4-噁唑啉类化合物的合成

2-碘苯甲酰肼与芳醛反应得到相应的酰腙(1),1再与丙酸酐脱水环化合成了3-N-丙酰基-2-芳基-5-(2-碘苯基)-1,3,4-噁唑啉类化合物,其结构经1H NMR,IR,MS和元素分析表征。     

Rapid acid hydrolysis of 5-aryl-3-(β-thiomorpholinoethyl)-1,2,4-oxadiazoles

The acid hydrolysis of a series of 5-aryl-3-(β-thiomorpholinoethyl)-1,2,4-oxadiazoles gave substituted benzoic acids and 2-amino-8-thia-1-aza-5-azoniaspiro[4.5]dec-1-ene chloride hydrate, whose structure was demonstrated by spectral methods and X-ray diffraction structural analysis.     

A facile retro-ene reaction of 5-(methoxyamino)-3-aryl-1,3,4-oxadiazol-2(3H)-ones

5-(N-Methoxy-N-methyl)amino-3-aryl-1,3,4-oxadiazol-2(3H)-ones 3 undergo a heteroretro-ene reaction in refluxing methanol in which the leaving enophile is formaldehyde. The resulting 5-(methylimino)-3-aryl-1,3,4-oxadiazolidin-2-one 4 may be viewed as a kinetic product which tautomerizes to the more stable 5-(methylamino)-3-aryl-1,3,4-oxadiazol-2(3H)-one 5 as the thermodynamic product. Comparison of calculated reaction energies reveals that the presence of the heterocyclic ring facilitates the retro-ene reaction, but the expulsion of formaldehyde is predicted to be highly exothermic even in its absence.     

Synthesis of 4-Acyl-5-aryl-3-hydroxy-1-(3-picolyl)-3-pyrroline-2-ones

Russian Journal of General Chemistry - Reaction of methyl esters of acylpyruvic acids with a mixture of aromatic aldehyde and 3-picolylamine gave...     

4-Functionally-substituted 3-heterylpyrazoles: XIX. 3-aryl-4-(5-isoxazolyl)pyrazoles

Oximes of 4-(4-pyrazolyl)-3-buten-2-onees obtained by successive reaction of 3-aryl-4-formylpyrazoles with acetone and hydroxylamine at the treatment with iodine suffered an oxidative cyclization yielding 3-aryl-4-(5-isoxazolyl)pyrazoles.     

3-芳基-5-(2-呋喃基)-4, 5-二氢吡唑衍生物的合成及其生物活性评价

二氢吡唑类化合物是一类具有良好生物活性的五元杂环化合物。本文以2-呋喃甲醛和4-氟苯乙酮为原料,经羟醛缩合和取代反应生成4’-二甲氨基呋喃查尔酮(2)后,与水合肼环化得到二氢吡唑中间体(3),再酰化得到9个未见报道的5-(2-呋喃基)-3-芳基-4, 5-二氢-1H-吡唑衍生物(4a-4i),其结构经IR、₁H NMR和₁₃C NMR确证。分别采用小鼠巨噬细胞Raw264.7模型和DHHP法初步测试了目标化合物的体外抗炎活性和抗氧化活性,结果表明,部分化合物具有潜在的抗炎活性和清除自由基活性,特别是化合物4b和4c的抗炎活性与阳性对照药地塞米松活性相当(IC₅₀值分别为7.84μM和10.52μM),而化合物3、4b、4c和4d在浓度为4mg/mL时对DPPH自由基的清除率均超过90%。     

4-(5-aryl-2-oxazolyl)phthalic anhydrides

4-(5-Aryl-2-oxazolyl)-substituted phthalic anhydrides were synthesized from 4-chloroformylphthalic anhydride and various -aminomethyl aryl ketones. The spectral-luminescence properties of solutions of the products in toluene and 5% NaOH solution were investigated. It is shown that the introduction of substituents with different electronic natures in the 5-phenyl ring of 4-(5-phenyl-2-oxazolyl) phthalic anhydride has a significant effect on the spectral-luminescence characteristics of the synthesized compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 35–37, January, 1979.     

Regioselective synthesis of 1-aryl-3,4-substituted/annulated-5-(methylthio)pyrazoles and 1-aryl-3-(methylthio)-4,5-substituted/annulated pyrazoles

[reaction: see text] Highly efficient and regioselective synthesis of 1-aryl-3,4-substituted/annulated-5-(methylthio)pyrazoles and 1-aryl-3-(methylthio)-4,5-substituted/annulated pyrazoles has been reported via cyclocondensation of arylhydrazines with either alpha-oxoketene dithioacetals or beta-oxodithioesters.     

Facile synthesis of 3-aryl-1-((4-aryl-1,2,3-selenadiazol-5-yl)sulfanyl)isoquinolines

A new series of 1,2,3-selenadiazoles containing an aryl or a 3-arylisoquinoline sulfanyl moiety at carbons 4 and 5, respectively, was prepared by cyclization of the respective semicarbazones in the presence of selenium(II) oxide and tetrahydrofuran at 70–75°C. Semicarbazones required for the reaction were obtained from 2-((3-arylisoquinolin-1-yl)sulfanyl)-1-phenylethanones, I, by a reaction with semicarbazide hydrochloride in ethanol/water mixture and potassium acetate base.     

Regioselective alkynylation of 2-aryl-4-chloro-3-iodoquinolines and subsequent arylation or amination of the 2-aryl-3-(alkynyl)-4-chloroquinolines

Palladium-CuI catalyzed Sonogashira coupling of 2-aryl-4-chloro-3-iodoquinolines with terminal acetylenes (1 equiv) in triethylamine afforded the 2-aryl-3-(alkynyl)-4-chloroquinolines as sole products. The 2-aryl-4-chloro-3-iodoquinolines coupled with excess terminal acetylenes (2.5 equiv) in dioxane/water to yield the 2-aryl-3,4-bis(alkynyl)quinoline derivatives in a one-pot operation. The 2-aryl-3-(alkynyl)-4-chloroquinolines were, in turn, subjected to arylation via Suzuki cross-coupling with arylboronic acid derivatives or amination with methylamine, respectively. The structures of the products of successive Sonogashira and Suzuki cross-couplings were also confirmed by X-ray crystallography.     

Transformation of trans-4-aryl-3-chloro-1-(2-chloroethyl)azetidin-2-ones into 3-aryl-2-(ethylamino)propan-1-ols via intermediate 1-(1-aryl-2-chloro-3-hydroxypropyl)aziridines and trans-2-aryl-3-(hydroxymethyl)aziridines

trans-4-Aryl-3-chloro-1-(2-chloroethyl)azetidin-2-ones, prepared through cyclocondensation of chloroketene and the appropriate imines in a diastereoselective way, were unexpectedly transformed into 3-aryl-2-(ethylamino)propan-1-ols using LiAlH(4) in THF under reflux. A stepwise analysis showed that the initially formed 1-(1-aryl-2-chloro-3-hydroxypropyl)aziridines were converted into trans-2-aryl-3-(hydroxymethyl)aziridines, most probably via N-spiro bis-aziridinium intermediates, which were subsequently prone to undergo ring opening by LiAlH(4) to afford 3-aryl-2-(ethylamino)propan-1-ols.     

Synthesis of ethyl 5-aryl-5-(trifluoromethyl)-4,5-dihydroisoxazole-3-carboxylates,exhibiting plant growth-regulating properties

Russian Chemical Bulletin - A convenient method for the synthesis of high-boiling-point α-(trifluoromethyl)styrenes was proposed. The regioselective synthesis of a series of ethyl...