Features of reactions of polyfluorinated ethyl 4-oxo-2-pnenyl-4H-chromene-3-carboxylates with N-nucleophiles

Ethyl 5,6,7,8-tetrafluoro-4-oxo-2-phenyl-4H-chromene-3-carboxylate in reactions with primary amines is characterized by a chromone-coumarin rearrangement affording 3-[amino(phenyl)methylene]-6,7,8-trifluoro-2H-chromene-2,4(3H)-diones, and ethyl 4-oxo-2-phenyl-5,6,7,8-tetrafluoro-4H-chromene-3-carboxylate characteristically adds the amine at the C² site of the flavone furnishing 3-amino-3-phenyl-2-(2,3,4,5-tetrafluoro-6-hydroxybenzoyl)acrylates which depending on the substituent at the amino group are capable of intramolecular cyclization into 3-[(alkylamino)(phenyl)methylene]-5,6,7,8-tetrafluoro-2H-chromene-2,4(3H)-dione or in the case of benzylamine substituent, into ethyl 1-benzyl-5-hydroxy-4-oxo-2-phenyl-6,7,8-trifluoro-1,4-dihydroquinoline-3-carboxylate. The main process in the reaction of tri- and tetrafluoroflavones with secondary amine (1-methylpiperazine) is the nucleophilic substitution at the C⁷ of flavone. In the reaction with 1,2-phenylenediamine 3-[(2-aminophenyl)amino]-3-phenyl-2-(2,3,4,5-tetrafluoro-6-hydroxybenzoyl)acrylate was obtained from tetrafluoroflavone and 1H-benzimidazol-2-yl(3,4,5-trifluoro-2-hydroxyphenyl)methanone, from trifluoroflavone.     

Crystal structures of ethyl-4-(5-bromo-2-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate and ethyl-1-methyl-15-oxo-2-oxa-14,16-diazatetracyclo [11.3.1.0<Superscript>3.12</Superscript>.0<Superscript>6.11</Superscript>]heptadeca-3,5,7,9,11-pentaene-17-carboxylate

The crystal structures of ethyl-4-(5-bromo-2-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate and ethyl-1-methyl-15-oxo-2-oxa-14,16-diazatetracyclo[11.3.1.0^3.12.0^6.11]heptadeca-3,5,7, 9,11-pentaene-17-carboxylate were determined by XRD, and the conformations of their structures were determined.     

Synthese von 2-Oxo-2H-pyran-5-Carboxylat-Derivaten

Synthesis of 2-Oxo-2H-pyran-5-carboxylate Derivatives 3-Substituted diethyl pent-2-enedioates are easily formylated by means of ethyl formate/TiCl⁴/4-methylmorpholine to produce the ethoxymethylene derivatives, which are smoothly cyclized either with HCOOH or PPA to corresponding 2-oxo-2H-pyran-5-carboxylate derivatives.     

A H, C and N NMR spectroscopic and GIAO DFT study of ethyl 5-oxo-2-phenyl-4-(2-phenylhydrazono)-4,5-dihydro-1H-pyrrole-3-carboxylate

¹⁵N-Labelled ethyl 5-oxo-2-phenyl-4-(2-phenylhydrazono)-4,5-dihydro-1H-pyrrole-3-carboxylate was synthesized by azo-coupling of diazotized aniline (using Na¹⁵NO₂ , 99% ¹⁵N) with ethyl 4,5-dihydro-5-oxo-2-phenyl-(1H)-pyrrole-3-carboxylate. The product was formed as a tautomeric hydrazone mixture as confirmed by ¹³C and ¹⁵N chemical shifts, and was obtained as a mixture of E and Z isomers according to ⁿJ(¹⁵N, ¹³C). A comparison of the ¹H NMR data with GIAO DFT calculations enabled determination of the configuration of the carboxy ester group in both isomers.     

Novel transformations of two kinds of chlorinated photo [2 + 2] cycloadducts of 2-pyrone-5-carboxylate

Novel reactions of 7,7-dichloro- and 7,7,8-trichloro-3-oxo-2-oxabicyclo[4.2.0]oct-4-ene-6-carboxylates 5 with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in alcohol gave pyrano[4,3-b]pyran-2,5-diones 8 via (Z)-(2H-pyran-2-on-3-yl)butenoates 7. On the other hand, the same treatment of 7,7,8-trichloro-2-oxo-3-oxabicyclo-[4.2.0]oct-4-ene-5-carboxylate 6b afforded 2-oxo-3-oxabicyclo[4.2.0]oct-4,7-diene-5-carboxylate 14 via cyclobutene formation and S_N2′ displacement by attack of the alkoxy anion.     

Synthesis and Characterization of Some Novel 3-Bromo-2-acetylthiophene Chalcones and Biological Evaluation of Their Ethyl-4-(3-bromothien-2-yl)-2-oxo-6-(aryl)cyclohex-3-ene-1-carboxylate Derivatives

Novel chalcones 1-(3-bromothien-2-yl)-3-(aryl)prop-2-en-1-ones derived from 3-bromo-2-acetylthiophene and their cyclization product with ethylacetoacetate such as 4-(3-bromothien-2-yl)-2-oxo-6-(aryl)cyclohex-3-ene-1-carboxylate derivatives were synthesized and studied by X-ray, analytical, and spectral methods. Compounds were screened for their anti-inflammatory, analgesic, and antimicrobial activities. The compound ethyl-4-(3-bromothien-2-yl)-2-oxo-6-(4-propoxyphenyl) cyclohex-3-ene-1-carboxylate 5c exhibited promising anti-inflammatory, analgesic and antibacterial activities.     

Facile Synthesis of 4-Oxo-4H-quinolizine-2-carboxamide Derivatives

A facile synthetic method for the construction of 2-substituted-4-oxo-4H-quinolizine-based core structure has been successfully developed. The synthesis made use of a one-pot Stobbe condensation followed by cyclization starting from the commercially available 2-pyridinecarbaldehyde. The structure of the formed 4-oxo-4H-quinolizine-2-carboxylate was fully confirmed by mass spectra, ¹H NMR and ¹³C NMR, correlation spectrography, heteronuclear multiple bond correlation, and heteronuclear single quantum coherence (HSQC) spectra. The ethyl carboxylate moiety was then further functionalized via direct aminolysis by a range of amines to afford the corresponding 4-oxo-4H-quinolizine-2-carboxamides 4a–i in moderate to good yields.     

Reactions of zinc enolates derived from 1-aryl-2-bromo-2-phenylethanone and 2-bromoindan-1-one with alkyl 2-oxochromene-and 6-bromo-2-oxochromene-3-carboxylates

Zinc enolates derived from 1-aryl-2-bromo-2-phenylethanone react with alkyl 2-oxochromene-3-carboxylates and methyl 6-bromo-2-oxochromene-3-carboxylate to give, respectively, alkyl 4-(2-aryl-2-oxo-1-phenylethyl)-2-oxochroman-3-carboxylates and methyl 6-bromo-4-(2-aryl-2-oxo-1-phenylethyl)-2-oxochroman-3-carboxylate as a single stereoisomer. Zinc enolates derived from 2-bromoindan-1-one react with alkyl 2-oxochromene-3-carboxylates to give alkyl 2-oxo-4-(1-oxoindan-2-yl)chroman-3-carboxylates as a single stereoisomer.     

The dramatic effect of thiophenol on the reaction pathway of ethyl 4-chloromethyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate with thiophenolates: ring expansion versus nucleophilic substitution

Ethyl 4-methyl-2-oxo-7-phenylthio-2,3,6,7-tetrahydro-1H-1,3-diazepine-5-carboxylate and/or ethyl 6-methyl-2-oxo-4-(phenylthiomethyl)-1,2,3,4-tetrahydropyrimidine-5-carboxylate were obtained in the reaction of ethyl 4-chloromethyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate with PhSNa or PhSK with or without PhSH, depending on the reagent ratio, reaction time, or temperature, as a result of ring expansion and/or nucleophilic substitution. The reaction pathway was affected strongly by the basicity-nucleophilicity of the reaction media. The results obtained were confirmed by reactions of 4-mesyloxymethyl-6-methyl-5-tosyltetrahydropyrimidin-2-one with PhSNa/PhSH and ethyl 4-chloromethyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate with NaCN/HCN or NaCH(COOEt)₂/CH₂(COOEt)₂.     

Synthesis and alkylation of new functionally substituted 4,4-dimethylpiperidin-2-ones

The reaction of ethyl isopropylidenecyanoacetate with ethyl 3-amino-3-thioxopropanoate gave rise to ethyl 4,4-dimethyl-6-oxo-2-thioxo-5-cyanopiperidine-3-carboxylate whose alkylation provided ethyl 2-benzylsulfanyl-4,4-dimethyl-6-oxo-5-cyano-1,4,5,6-tetrahydropyridine-3-carboxylate, ethyl 5-benzyl-2-benzylsulfanyl-4,4-dimethyl-6-oxo-5-cyano-1,4,5,6-tetrahydropyridine-3-carboxylate, and ethyl 7,7-dimethyl-5-oxo-6-cyano-3,5,6,7-tetrahydro-2H-thiazolo[3,2-a]pyridine-8-carboxylate.     

Synthesis of alkyl 4-alkyl-2-hydroxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylates as peptidomimetic building blocks

A general synthesis of new alkyl 4-alkyl-2-hydroxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylate peptidomimetic building blocks from the corresponding alkyl 3-oxo-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylates through carbanion oxidation is described.     

2-氨基-4-羰基噻吩的Knoevenagel反应

在碳酸钾等无机碱的存在下,异硫氰酸酯和4-氯乙酰乙酸乙酯反应生成2-氨基-4-羰基-4,5-二氢噻吩-3-甲酸乙酯。该化合物显示了与醛基的反应活性,即Knoevenagel反应,本文对该噻吩化合物的Knoevenagel反应位点选择性进行了研究。运用Gaussian03程序对化合物进行了几何全优化和相应的电荷、轨道能量分析研究。     

Synthesis of 5,8-dihydro-5-oxo-2-(3- or 4-pyridinyl)-pyrido[2,3-d]pyrimidine-6-carboxylic acids and the reinvestigation of the thermal cyclization of diethyl (2-hydroxy-4-pyrimidinyl)amino-methylenemalonate

Diethyl [2-(3- or 4-pyridinyl)-4-pyrimidinyl]aminomethylenemalonates 5 prepared by the reaction between 2-(3- or 4-pyridinyl)-4-pyrimidinamines 3 and diethyl ethoxymethylenemalonate ( 4 ) were thermally cyclized to afford ethyl 5,8-dihydro-5-oxo-2-(3- or 4-pyridinyl)pyrido[2,3-d]pyrimidine-6-carboxylates 6 . The later were alkylated with ethyl iodide and then saponified to give 5,8-dihydro-8-ethyl-5-oxo-2-(3- or 4-pyridinyl)pyrido-[2,3-d]pyrimidine-6-carboxylic acids 2 . Thermal cyclization of diethyl (2-hydroxy-4-pyrimidinyl)amino-methylenemalonate ( 8 ) gave ethyl 1,6-dihydro-4,6-dioxo-4H-pyrimido[1,6-a]pyrimidine-3-carboxylate ( 10 ) instead of ethyl 5,8-dihydro-2-hydroxy-5-oxopyrido[2,3-d]pyrimidine-6-carboxylate ( 9 ) as previously claimed.     

Hydrolytic opening of the quinazoline ring in 3-furfuryl-4-oxo-3,4-dihydroquinazoline derivatives

Ethyl 3-furfuryl-4-oxo-3,4-dihydroquinazoline-2-carboxylate extremely readily undergoes hydrolysis in acid, alkaline, or neutral medium with formation of 2-(2-ethoxy-1,2-dioxoethylamino)-N-furfurylbenzamide. The reaction of ethyl 3-furfuryl-4-oxo-3,4-dihydroquinazoline-2-carboxylate with phenylmagnesium bromide yields N-furfuryl-2-(2-hydroxy-2,2-diphenyl-1-oxoethylamino)benzamide as a result of hydrolytic cleavage of the quinazoline ring.     

Five-membered dioxoheterocycles: XCIX. Reaction of 1-aryl-4-aroyl-5-methoxycarbonyl-1H-pyrrole-2,3-diones with indoles. Crystal and molecular structure of substituted 2-(indol-3-yl)pyrrole

1-Aryl-4-aroyl-5-methoxycarbonyl-1H-pyrrole-2,3-diones react with indole and 2-methylindole with the formation of methyl 1-aryl-3-aroyl-4-hydroxy-2-(1H-indol-3-yl)-5-oxo-2,5-dihydro-1H-pyrrole-2-carboxylates. Crystal and molecular structure of methyl 3-benzoyl-4-hydroxy-2-(2-methyl-1H-indol-3-yl)-5-oxo-1-phenyl-2,5-dihydro-1H-pyrrole-2-carboxylate was examined.     

An efficient synthesis of 1-oxo-1,2-dihydrobenzo[b][1,6]naphthyridine-4-carbonitriles

Ethyl α-(dimethylaminomethylene)-2-cyanomethyl-4-phenylquinoline-3-carboxylate(2) as new synthons directed to 1-oxo-1,2-dihydrobenzo[b][1,6]naphthyridine-4-carbonitriles was obtained by the condensation of ethyl 2-cyanomethyl-4-phenylquinoline-3-carboxylate(1) and N,N-dimethylformamide dimethyl acetal(DMFDMA).Reaction of this enamine with primary amines(3) in HOAc-DMF at120 ℃then affords 2-substituted 1-oxo-1,2-dihydrobenzo[b][1,6]naphthyridine-4-carbonitrile derivatives(4) in good yields by a tandem addition-elimination-cyclization reaction.     

Five-membered 2,3-Dioxoheterocycles: LIX. Reaction of 3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with Acyclic β-Enaminoesters. Crystal and Molecular Structure of Ethyl 3-Benzoyl-4-hydroxy-1-o-hydroxyphenyl-5-oxo-2,3-dihydro-1H-pyrrolo-2-spiro-3′-(5-methyl-2-oxo-2,3-dihydro-1H-pyrrolo-4-carboxylate)

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones react with substituted alkyl 3-amino-2-propenoates to form substituted alkyl 3-aroyl-4-hydroxy-1-o-hydroxyphenyl-5-oxo-2,5-dihydro-1H-pyrrole-2-spiro-3′-(2-oxo-2,3-dihydro-1H-pyrrole-4-carboxylates). Crystal and molecular structure of ethyl 3-benzoyl-4-hydroxy-1-o-hydroxyphenyl-5-oxo-2,5-dihydro-1H-pyrrole-2-spiro-3′-(5-methyl-2-oxo-2,3-dihydro-1H-pyrrole-4-carboxylate) was investigated.     

Carbon-13 nuclear magnetic resonance study of a new ring-chain tautomerism of some pyridazine derivatives

The ¹³C NMR spectra of a number of pyridazine derivatives have been recorded in DMSO-d₆ solution and analysed. Examination of the most diagnostic resonances, with particular emphasis on those arising from the pyridazine ring system, enabled the ready establishment of the presence of a ring-chain tautomerism in 5-(o-aminophenylcarbamoyl)pyridazine-4-carboxylic acid, methyl 5-(o-aminophenylcarbamoyl)pyridazine-4-carboxylate, 5-(o-aminophenylcarbamoyl)-3,6,-dimethylpyridazine-4-carboxylic acid and 5-(2-amino-1,2-dicyanovinylenecarbamoyl)pyridazine-4-carboxylic acid. This gave rise to 3′,4′-dihydro-3′-oxospiro[pyridazine-5(2H),2′(1H)-quinoxaline]-4-carboxylic acid, methyl 3′,4′-dihydro-3′oxospiro[pyridazine-5(2H),2′(1′H)-quinoxaline]-4-carboxylate, 3′,4′-dihydro-3′-oxo-3,6-dimethylspiro[pyridazine-5(2H), 2′(1′H)-quinoxaline]-4-carboxylic acid and 5-oxo-2,3-dicyano-1,4,8,9-tetraazaspiro[5.5]undeca-2,7,10-triene-11-carboxylic acid, respectively.     

Methanolysis and hydrolysis of derivatives of methyl 2,5- and 4,5-dihydrofuran-2-carboxylates

Methyl 2,5-dimethoxy-2,5-dihydrofuran-2-carboxylate is formed in the reaction of HCl-CH₃OH with methyl 5-nitro-2-acetoxy-2,5-, 5-nitro-4-acetoxy-4,5-, and 2,5-diacetoxy-2,5-dihydrofuran-2-carboxylates, whereas methyl 2,5-dioxo-3-pentenoate bis(2,4-dinitrophenylhydrazone) and 4-oxo-2-penten-1,5-dioic acid 2,4-dinitrophenylhydrazone are isolated in the presence of 2,4-dinitrophenylhydrazine. Methyl 5-nitrofuran-2-carboxylate is formed by treatment of methyl 5-nitro-2-acetoxy-2,5-dihydrofuran-2-carboxylate with aqueous solutions of acetic or phosphoric acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1600–1603, December, 1977.     

A facile synthetic route to 2-trifluoromethyl-substituted polyfunctionalized chromenes and chromones

A method for the preparation of methyl 4-hydroxy-2-(trifluoromethyl)-4H-chromenes-3-carboxylate derivatives 3a–j from readily available trifluoromethylated building block methyl (Z)-2-bromo-4,4,4-trifluoro-2-butenoate 1 was described. Treatment of 3a–j with Sarrett reagent in CH₂Cl₂ generated methyl 4-oxo-2-(trifluoromethyl)-chromene-3-carboxylate derivatives 4a–h with moderate to good yields, which can be converted to 2-trifluoromethyl-substituted multifunctional benzoxepins through cyclopropanation and Lewis acid-catalyzed ring opening.