Synthesis and stereochemistry of 2-benzylidene-4-carbethoxy-5-methyl-3-(2H)-furanones

The title products were obtained by Knoevenagel condensation between 4-carbethoxy-5-methyl-3-(2H)furanone and substituted benzaldehydes (or 4-chloroacetophenone). The configuration of the resulting compounds was investigated by ¹H nmr using the lanthanide shift reagent.     

Use of two-dimensional spectroscopy for the determination of the stereochemical structure of 3-carbethoxy-2-methyl-7a-(4-carbethoxy-5-methyl-2-furyl)-3a,4,5,6,7,7a-hexahydrobenzofuran

Homo- and heteronuclear two-dimensional correlation spectra, as well as J-resolved spectra with selective excitation, were used to analyze in detail the stereochemical structure of 3-carbethoxy-2-methyl-7a-(4-carbethoxy-5-methyl-2-furyl)-3a,4,5,6,7,7a-hexahydrobenzofuran, obtained by the reaction of cyclohexenyl-acetylene with acetoacetic ester in the presence of a manganese(III) salt. It was shown that the use of the long-range ¹³C-¹H coupling constants is a very effective method for the determination of the conformation of the molecule. The stereochemical aspects of the reaction of cyclohexenylacetylene with acetoacetic ester is discussed.cis-Configuration has an axial-equatorial arrangement of the C_(7a)-O and C_(3a) bonds, trans-configuration has a diequatorial (diaxial) arrangements of these bonds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 167–171, February, 1991.     

Stereochemical studies of 5-methyl-3-(substituted phenyl)-5-[(substituted phenyl) hydroxy methyl]-2-thiooxazolidin-4-ones

The synthesis and stereochemical aspects of the aldol products, 5-methyl-3-(substituted phenyl)-5-[(substituted phenyl) hydroxy methyl]-2-thiooxazolidin-4-ones, are discussed.     

Vilsmeier formylation of 2-methyl-3 -carbethoxy-5-methoxy- and 2-methyl-5-methoxyindoles

The corresponding 6- and 3-formyl derivatives were obtained by formylation of 2-methyl-3-carbethoxy-5-methoxy- and 2-methyl-5-methoxyindole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 339–341, March, 1971.     

2-甲酰基-3-乙酰基-4-甲基-5-苄氧羰基吡咯的合成

甲酰基乙酰基甲基苄氧羰基吡咯;二甲基乙酰基苄氧羰基吡咯;加成环化;选择性氧化     

Synthesis of 3-substituted-4-methyl-5-acetyl-4-thiazoline-2-thione

The reaction of various potassium salts [RNHC(=S)SK, R = N(CH₃)₂, morpholino, piperidino, and hexahydro-1-(1H)-azepinyl] with 3-chloro-2,4-pentanedione in ethanol at 25–30° afforded the 1-acetylacetonyl substitutedaminodithiocarbamates 1–4 [RNHC(=S)SCH(COCH₃)₂]. Under refluxing conditions, the same reactants gave the heterocyclic compounds 5–8. Possible mechanism and supporting ir, nmr and mass spectral data are discussed.     

Acid — Base properties of 3,4-dimethyl-2-thiazolone, 4-methyl-2-thiazolone,and 5-acetyl-4-methyl-2-thiazolone

In contrast to 2-methoxy-4-methylthiazole and 2,4-dimethylthiazole, the protonation of 3,4-dimethyl-2-thiazolone does not proceed in media with acidities up to H₀=–3.99. The acidity of N-H increases by 2.4 orders of magnitude on passing from 4-methyl-2-thiazolone to its 5-acetyl derivative. The data obtained from a study of the acid-base properties in conjunction with the results of calculations of the 3,4-dimethyl-2-thiazolone and thiazole molecules by the MO method make it possible to conclude that there is a charge in the 5 position of 2-thiazolones and that this is the reason for the facile acylation of these compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1622–1625, December, 1972.     

Synthesis of 2-carbethoxy-3-methyl-4-hydroxybenzofuran derivatives

A number of 2-.carbethoxy-3-methylbenzofuran derivatives were synthesized. A 5,5-gem-dibromo derivative was obtained in the bromination of 2-carbethoxy-3-methyl-4-oxo-4, 5,6,7,tetrahydrobenzofuran. Dehydrobromination of this, dibromo derivative gave 2-carbethoxy-3-methyl-4-hydroxy-5-bromobenzofuran. Depending on the structure of the starting compound and the brominating agent, the bromine in the bromination of 2-carbethoxy-3-methyl-4-hydroxy- and 4-acetoxybenzofurans with bromine and N-bromosuccinimide is incorporated either in the methyl group or in 5 and 7 positions of the benzofuran ring. The nitration of 2-carbethoxy-3-methyl-4-hydroxybenzofuran and its bromo derivative leads to 5-nitro- and 5,7-dinitrobenzofuran derivatives. The structures of the synthesized benzofuran derivatives were established by means of the PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 27–29, January, 1980.     

Recyclization of Acylation Products of 2-Aryl-5-hydrazino-4-(dialkoxyphosphoryl)oxazoles

Russian Journal of General Chemistry -     

2-羟基-5-甲基-5-(4-甲基戊烯-3-)基四氢呋喃的合成

本文研究了一类羰基化合物-酮类为原始料(选用了来源丰富, 价格低廉的6-甲基-5-庚烯酮-2), 经格氏反应水解, 环化及醚化即合成了2-羟基-5-(4-甲基戊烯-3-)基四氢呋喃。     

Extraction,complex formation and spectrophotometric determination of iron(III) with 2-carbethoxy-5-hydroxy-1-(4-tolyl)-4-pyridone

Summary The extraction of iron(III) from aqueous HCl, H₂SO₄, HClO₄, HNO₃ solutions by 2-carbethoxy-5-hydroxy-1-(4-tolyl)-4-pyridone (HA) dissolved in CHCl₃ has been studied. Quantitative extraction of iron(III) is achieved if the concentration of the acids does not exceed 1N. The composition of the iron (III)—HA complex formed in the organic phase was investigated spectrophotometrically, radiometrically and by analysis of the isolated species. In the aqueous phase iron (III) and HA form three different complexes, depending on the initial iron: HA concentration ratio and the pH of the solution. They are the violet FeA²⁺, the orange-red FeA₂ ⁺ and the orange-yellow FeA₃. The latter is identical with the complex found in the organic phase, which was isolated as a solid crystalline material and characterized by elemental analysis and infrared spectroscopy. A spectrophotometric method for the determination of iron(III) in the aqueous phase and in the chloroform solution, by extraction with HA, is described.

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Zusammenfassung Die Extraktion von Fe(III) aus wäßrigen Lösungen von HCl, H₂SO₄, HClO₄ oder HNO₃ mit 2-Carbäthoxy-5-hydroxy-1-(4-tolyl)-4-pyridon (HA) in chloroformischer Lösung wurde untersucht. Sie verläuft quantitativ, wenn die Konzentration der Säure nicht größer ist als 1-n. Die Zusammensetzung des Fe(III)-HA-Komplexes in der organischen Phase wurde spektrophotometrisch, radiometrisch und durch Analyse der isolierten Substanz untersucht. In wäßrigem Milieu bilden Eisen(III) und HA drei verschiedene Komplexe je nach dem anfänglichen Konzentrationsverhältnis Fe(III): HA und je nach dem pH der Lösung. FeA²⁺ ist violett, FeA₂ ⁺ ist orange-rot und FeA₃ orangegelb. Diese Verbindung ist mit dem in der organischen Phase gefundenen Komplex identisch, der in kristallisierter Form isoliert und durch Elementaranalyse und IR-Spektrometrie charakterisiert wurde. Eine spektrophotometrische Methode zur Eisen(III)-Bestimmung in wäßriger Phase und in chloroformischer Lösung durch Extraktion mit HA wurde beschrieben.

     

Recyclization and photorearrangements of 2-acetyl-4,4-dialkyl-2-buten-4-olide oximes

Recyclization to derivatives of dihydro-1,2-oxazines was realized by the reaction of 2-acetyl-3-methyl-4,4-dialkyl-2-buten-4-olide oximes with sodium borohydride. The UV-irradiation-initiated Beckmann rearrangement of the oximes cited above leads to 4,4-dialkyl-2-buten-4-olide-2-carboxylic acid N-methylamides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 157–160, February, 1989.