Spectroscopic detection of theendo-enol form of 2-acetylcyclopentane-1,3-dione

According to vibrational spectroscopic data, in the gas phase at 280 °C and in crystals prepared by sublimation, 2-acetylcyclopentane-1,3-dione was established to exist not as trione 1 but as the enol-form 2 with an exo-cyclic C=C bond (v(C=C) = 1593 cm^–1) and an intramolecular hydrogen bond. The enol 3 prepared by crystallization from CCl₄ is also stabilized by an intramolecular H-bond but has anendo-cyclic C=C bond (v(C=C) = 1545 cm^–1). In a trichloroethylene solution, both theexo- andendo-enol forms co-exist, and the percentage of the latter is 11 %. The frequencies in the vibrational spectra have been assigned using the normal coordinate calculation of2, 3, and their OD-analogs. The mechanism of tautomer transfer is discussed in terms of PMO theory.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 57–62, January, 1994.The authors are grateful to professor J. G. Ramos (Madrid Institute of Optics) for making it possible to record the far IR and Raman spectra in his laboratory, to Dr. V. Z. Kurbako for the registration of spectra and its discussion, and to Dr. N. A. Kubasova for recording the Raman spectra with a Coderg Ar-300 instrument.     

Zur Kinetik der Bildung von Arylaminomethylenverbindungen aus Triethoxymethan,Arylaminen und CH2-aciden Verbindungen in einer Dreikomponentenkondensation

Condensation of triethoxymethane and aniline with dimedone gives 2-anilinomethylene dimedone as the main product. An¹H-NMR-spectroscopic investigation of the kinetics in chloroform-d ₁ and methanol-d ₄ shows different rate determining steps in these solvents. There are two predominant rate determining steps in a complicated multistep reaction sequence.The initial one involves condensation of aniline with triethoxymethane to form diphenyl formamidine via ethyl phenyl formimidate. The second step involves reaction of the intermediate diphenyl formamidine with dimedone. The rates are strongly dependent upon the nature of the solvent and the concentration of catalytic acid. In methanol the reaction of dimedone with the intermediate diphenyl formamidine is rate determining. For preparative purposes the isolation of the intermediate diphenyl formamidine and the subsequent use of less polar solvents offer an advantage, because the second step is found to be accelerated.

6. Mitt.:Wolfbeis, O. S., Mh. Chem.112, 369 (1981).     

Vanillin esters in reactions with indan-1,3-dione

2-Methoxy-4-(12-oxo-12H-benzo[f]indeno[1,2-b]quinolin-13-yl)phenyl esters of carboxylic acids were synthesized by the three component condensation of indan-1,3-dione, 2-naphthylamine, and O-acylvanillin. 2-Arylidenindan-1,3-diones formed during the reaction were isolated. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1408–1413, September, 2006.     

Optisch aktives 1,3-Diferrocenyl-1,3-diphenyl-allen

The title compound 2 was prepared by thermal dehydration of 1,3-diferrocenyl-1,3-diphenyl-propenol (24) with 70% yield.24 was accessible from 1,3-diferrocenyl-propanedione-1,3 (25) in two steps with 10% overall yield: Treatment of25 with phenyllithium gave 1,3-diferrocenyl-3-phenyl-propenone (8) which after repeated reaction with phenyllithium afforded24.Partial optical resolution of2 was achieved by chromatography on triacetyl cellulose in ethanol, whereby both (+)- and (–)-2 were obtained with different enantiomeric purities as could be deduced from the CD-spectra with -values of +0.18 and –1.64, resp., at 480 nm.Attempts to prepare 1,3-diferrocenyl-allene and 1,3-diferrocenyl-1-phenyl-allene failed. In this context several 1,3-diferrocenyl-propenols,-propenones,-propenes,-propanones,-propanes and-butadienes were obtained.

62. Mitt.:M. Benedikt undK. Schlögl, Mh. Chem.109, 805 (1978).     

Die Photoenolisierung,Autoxidation und Dimerisation von 2-Isobutyliden-1,3-indandion

The title compound,1, slowly decomposes in solution by autodixation, especially in daylight. The chemism of this photoinduced autoxidation has been investigated.Upon irradiation1 passes to the brick red isolable dienol2. The quantum yield is 0.3 at 313 nm in methanol. In solution an equilibrium is set up within several minutes between2 and the colorless deconjugated3. Unpolar or moderately polar solvents shift the equilibrium completely to3, whereas in highly polar solvents2 and3 coexist. In the dark the equilibrium12 (ca. 501 in methanol) is established very slowly.3 upon irradiation reacts further to dimer8. 2 instantaneously reacts with oxygen. With high oxygen concentrations, hydroperoxide9 is formed, with lower ones dehydrodimer10, inter alia.9 and10 may further form12, 14, and15. These reactions, together with ESR spectroscopy, point to a central role of the free radical13 both in the autoxidation and in the reaction1014.Basic catalysis sets up an equilibrium between1 and its dimer,17. The photoreaction12 has been investigated by sensitizing and quenching experiments.

34. Mitteilung:J. Bitter, J. Leitich, H. Partale, O. E. Polansky, W. Riemer, U, Ritter-Thomas, B. Schlamann undB. Stilkerieg, Chem. Ber., im Druck.     

2H-Isoindol-4,7-dione durch Addition von Azomethinyliden an 1,4-Benzochinone

Summary A new approach to the synthesis of 2H-isoindole-4,7-diones is described. Heating -amino acids with carbonyl compounds generates azomethine ylides through the elimination of water and carbon dioxide. The ylides were captured by quinones forming 2H-isoindole-4,7-diones, 2,3,3a,7a-tetrahydro-1H-isoindole-4,7-diones and 2,3-dihydro-1H-pyrrolo[2,1-a]isoindole-6,9-diones. The structures were established on the basis of spectroscopy (NMR, mass).

Herrn Univ.-Prof. Dr. G. Zigeuner zum 70. Geburtstag gewidmet     

Kondensierte Chinazolinium-Verbindungen

Neighbouring effects during mercuryEDTA dehydrogenation yield with1 the vinylogous acylamidinium compound11 and with2, 3 and6 the vinylogous amidinium derivatives8–10.

Herrn Professor Dr.H. Bretschneider zur Vollendung des 75. Lebensjahres gewidmet     

Di-isophorone and related compounds. Part 7. Syntheses and properties of 1-hydroxydi-isophor-2(7)-ene-3,4-dione

1-Hydroxydi-isophor-2(7)-ene-3,4-dione (4), the -diketone derived from the parent di-isophorone, is obtained by several routes. Its formation by the hydrogenation of the corresponding 2,7-epoxide3 confirms its assigned structure. The action of alkali on 4-substituted 8-bromodi-isophor-2(7)-en-3-ones yields, presumably by a successive bimolecular (SN2) substitution and hydrolysis, the 4,4-dihydroxy-precursor, from which the 3,4-diketone4 arises by loss of water. In yet another approach,4 is produced by the hydrolysis of its 4-monohydrazone, which is independently accessible from 8-bromo-1-hydroxydi-isophor-2(7)-en-3-one (8). In acidic media, the yellow diketone4 enolises to the stable isolable colourless 1,3-dihydroxydi-isophora-2,7-dien-4-one (19); the action of alkali reverses the process. Both forms of the compound yield the same 1-acyl-derivatives and 4-hydrazones.Part 6:Davies, P. R., Kurzer, F., Morgan, A. R. Mh. Chem.111, 1097 (1980).     

微波辅助合成1,3-二苯基-2-吡唑啉

以取代苯肼盐酸盐(1)和β-二甲胺基苯丙酮盐酸盐(2)为原料, 在微波辐射条件下一步合成了一系列1,3-二苯基吡唑啉类化合物3. 本方法具有操作简单、反应时间短、产率高等特点.     

neue Heterocyclisierungen mit Malonestern 1,3-Dithiole; 1,3-Oxathiole; Δ2-Oxazoline und das Vinylendipyridiniumdikation

The reaction of diethyl bromomalonate (1) or diethyl diazomalonate (6) with benzoyl isothiocyanate (2) proceeds via the carbene intermediates4, 7 or12 to afford the 1,3-dithiole5, the 2-oxazoline8 or the 1,3-oxathioles9 depending upon the catalyst employed. In contrast, the bis(ethoxycarbonyl)methylpyridinium bromides14 upon treatment with benzoyl isocyanates15 in pyridine give rise to vinylene dipyridinium dibromides18.

     

Derivatives of 2-benzazepine-1,3-dione

The reactions of the di(acid chloride) of 2-carboxy-3,4-dimethoxyphenylthiopyruvic acid with 1-aminoadamantane and with thiosemicarbazide take place with the closure of a seven-membered ring and the formation of 1,2-dihydro-(3H)-2-benzazepine-1,3-dione. On reaction with monochloroacetic acid, 4-mercapto-8, 9-dimethoxy-2-(N-thioureido)-1, 2-dihydro-(3H)-2-benzazepine-3-dione is converted into a derivative of thiazolidine-2,4-dione 2-hydrazone, which readily takes part in condensation reactions with oxo compounds forming 5-ylidene derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 29–32, January, 1984.     

Reaction of 1,3-Dibromo- and 1,3-Dichloroacetone with 2-Aminoazaheterocycles

The reactions of 1,3-dibromoacetone with 2-aminoazines and 2-aminoazoles has been carried out for the first time and the pure intermediate quaternary salts have been isolated. They undergo cyclization to the corresponding imidazoazines and imidazoazoles containing a bromomethyl group. Similar condensations were carried out with 1,3-dichloroacetone.     

Solid-state tautomerism in 2-carboxyindan-1,3-dione

The structure of 2-carboxyindan-1,3-dione was investigated using a combination of quantum-chemical calculations and solid-state NMR and IR spectroscopy. Due to poor solubility of the compound in different solvents, no single crystals could be obtained. Two dimeric structures formed from the tautomers of 2-carboxyindan-1,3-dione are likely to coexist in the solid state. The dimers interconvert via intramolecular proton transfer in one of the tautomeric forms constituting the dimers. The energy barrier of the intramolecular proton transfer reaction is calculated as 5.82 kcal mol(-1) at the MP2/6-31++G level of theory.     

Asymmetric cyclization-carbonylation of 2-propargyl-1,3-dione

The first example of asymmetric cyclization-carbonylation of 2-propargyl-1,3-dione 1 catalyzed by palladium(II) with chiral bisoxazolines (C.H.-BOX) was investigated. The use of bulky alcohols increased the ee of the products 2. The product 2d was converted into bicyclic enones 7 and 8, a useful intermediate for the synthesis of natural products.     

Benzothiazolo[3,2-c]-1,3-dioxolo[4,5-g]quinazolines

Zusammenfassung Es wurde eine Reihe von 5,12a-Dihydro-6-alkyl/aryl-6H-benzothiazolo [3,2-c]-1,3-dioxolo[4,5-g]chinazoline, sowohl mitcis-als auchtrans-ständigen Wasserstoffatomen an Kohlenstoff 6 und 12a, synthetisiert. Ebenso wurden auch Verbindungen dieses Systems mit Thiazol an Position 6 hergestellt. Die Strukturen wurden mittels IR- und NMR-spektroskopischen Daten abgesichert.

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Benzothiazolo[3,2-c]-1,3-dioxolo[4,5-g]quinazolines

Some 5,12a-dihydro-6-alkyl/aryl-6H-benzothiazolo[3,2-c]-1,3-dioxolo [4,5-g]quinazolines withcis as well astrans stereochemistry of the hydrogens at carbon 6 and 12a have been synthesised. The synthesis of another series of compounds of the above system with thiazole ring at position 6 has also been accomplished. The structures have been established on the basis of IR and PMR data.

     

IR-spectral study of photoinduced tautomerization in 1,3-diphenyl-pyrazol-5-one

The UV-photoinduced prototropic isomerization of 1,3-diphenyl pyrazol-5-one (DPhP) embedded in polyvinyl chloride (PVC) film is studied by means of difference in IR spectral analysis. The initially existing CH-form in non-irradiated compound is transformed to NH-form, and a hydrochloride salt is stabilized because of the photodegradation of the PVC. An additional comparative IR spectral study of DPhP in different solutions as well as of its hydrochloride salts in solid state is also carried out.     

Solid-state structures of 2-(4-hydroxyphenyl)-substituted phenalene-1,3-dione and indan-1,3-dione

The structure of 2-(4-hydroxyphenyl)-substituted indan-1,3-dione and phenalene-1,3-dione is investigated using a combination of solid-state NMR, single crystal X-ray analyses and quantum chemical calculations. It is shown that 2-(4-hydroxyphenyl)-1,3-indandione exists as a diketo tautomer while 2-(4-hydroxyphenyl)-1,3-phenalenedione exists in the enol form.