Synthesis of new functionally substituted fullerenopyrrolidines

New fullerenopyrrolidines were synthesized by the three-component reactions of fullerene C₆₀, N-methylglycine, and aromatic aldehydes, viz., N,N-bis(2-chloroethyl)-4-aminobenzaldehyde, N-(2-chloroethyl)-N-methyl-4-aminobenzaldehyde, indole-3-carbaldehyde, 4-phenylbenzaldehyde, and anthracene-9-carbaldehyde. The structures of the resulting compounds were established by spectroscopic methods.     

NMR studies of 4(3H)-quinazolinones and 4(3H)-quinazolinethiones

Summary Unambiguous¹H and¹³C NMR assignments for 4(3H)-quinazolinones1–6 and their corresponding 4-thiones7–12 have been made. This resulted in the revision of the previous assignments for the two benzenoid carbons (C-5 and C-8) of quinazolinones1,2,4, and5. Thionation of the nucleophilic amides1–6 has been found to cause a distinct change in the¹³C chemical shift of particularly C-4, but also of those of C-4a, C-5, and C-8a. One-bond and several long range heteronuclear coupling constants for the compounds have also been measured.

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Kernresonanzspektroskopie von 4(3H)-Chinazolinonen und 4(3H)-Chinazolinthionen

Zusammenfassung Die¹H- und¹³C-NMR-Spektren der 4(3H)-Chinazolinone1–6 und ihrer entsprechenden 4-Thione7–12 wurden zugeordnet. Dabei zeigte sich, daß eine frühere Zuordnung der beiden benzoiden Kohlenstoffe (C-5 und C-8) der Chinazolinone1,2,4 und5 falsch war. Ersatz des Sauerstoffs durch Schwefel in den nukleophilen Amiden1–6 führt insbesondere für C-4, aber auch für C-4a, C-5 und C-8a zu einer deutlichen Änderung der chemischen Verschiebung. Heteronukleare Kopplungskonstanten über eine und über mehrere Bindungen wurden bestimmt.

     

Convenient synthesis and NMR spectral studies of variously substituted <Emphasis Type="Italic">N</Emphasis>-methylpiperidin-4-one-<Emphasis Type="Italic">O</Emphasis>-benzyloximes

Abstract  A series of variously substituted N-methylpiperidin-4-one-O-benzyloximes were synthesized by three different methods. Among them, the direct conversion of 2,6-diarylpiperidin-4-ones into the corresponding oxime ethers (method A) was proved to be better than the other two methods in the sense of good yield, convenience, easy work-up and quick reaction time. All the synthesized compounds are characterized by IR, Mass and NMR (¹H NMR, ¹³C NMR, ¹H-¹H COSY, ¹H-¹³C COSY and HMBC) spectral studies. The conformational preference of the synthesized oxime ethers with/without alkyl and aryl substituents at C-3/C-5 and C-2/C-6 is discussed using the spectral data. The observed chemical shifts and coupling constants suggest that the synthesized oxime ethers adopt chair conformation with equatorial orientation of all the substituents, whereas 1-methyl-3-isopropyl-2,6-diphenylpiperidin-4-one-O-benzyloxime also exists in boat conformation. Based on the NMR data, the effects of oximination on ring carbons and their associated protons and alkyl substituents are discussed. In addition, the effect of NMe group on the 2,6-diarylpiperidin-4-one-O-benzyloximes was also studied. Graphical abstract        

Dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes with lanthanum metal

It was found that lanthanum metal caused the dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes to generate the corresponding benzynes and o-quinodimethanes. When o-dihalogen substituted arenes were allowed to react with lanthanum metal in the presence of dienes, the Diels-Alder products between benzyne and dienes were formed in moderate to good yields. Similarly, the Diels-Alder adducts of o-quinodimethane with dienophiles were obtained, in the reaction of α,α′-dibromo-o-xylenes with lanthanum metal in the presence of dienophiles.     

N-Oxides of polychloropyridines.13C NMR study

The effect ofN-oxidation of a series of polychloropyridines on¹³C NMR parameters has been studied. It has been established that inN-oxides of polychloropyridines an electric field through-space effect of theN-oxide group predominates in the shielding of the -carbon atom compared to the other carbon atoms. A linear correlation between¹³C NMR chemical shifts and total charge densities calculated by the MNDO method for the carbon atoms ofN-oxides of polychloropyridines has been found.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2425–2428, December, 1995.The authors are grateful to V. V. Kolchanov for help in the synthesis of compounds under study.     

o-benzoquinone photoreduction products in the presence of N,N-dimethylanilines

Photoreduction of o-benzoquinones in the presence of para-substituted N,N-dimethyl-anilines under irradiation at λ ≥ 500 nm affords pyrocatechol monoethers of the 2-(amino-methoxy)phenol type. In the subsequent dark reaction, these monoethers undergo quantitative decomposition by a heterolytic mechanism to give the corresponding pyrocatechols and nitrogen-containing compounds. The rate of this decomposition decreases with decreasing size of the substituent at the position adjacent to the ether bond that is formed upon photoreduction. The redox characteristics of such pyrocatechol monoethers can serve as the criterion of their stability. A weakening of the electron-withdrawing properties of quinones and the electron-donating properties of amines leads to an increase in stability of their reaction products. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1528–1535, September, 2006.     

Quantitative 2H NMR spectroscopy. 1. Thermodynamic H/D isotope effects in N,N-dimethylformamide and cyclopentadiene molecules

A new method for quantification of the relative distribution of deuterium in molecules is proposed. The technique is based on the lineshape analysis in the ²H NMR spectra obtained at the natural abundance level of deuterium with allowance for inhomogeneity of the magnetic field. The equilibrium thermodynamic H/D isotope effects for hindered rotation about the C—N bond in the N,N-dimethylformamide molecule and for prototropic exchange in the cyclopentadiene molecule were determined. The results obtained agree with those of DFT calculations of the vibrational energies.     

Isomerization of substituted tricyclic 4,5-dihydropyrazoles

Summary The acid and base catalyzed isomerization of some tricyclic 2-pyrazolines with N-Carbamoyl-,N-thiocarbamoyl-and N-phenyl substituents was investigated. Starting fromcis ortrans 3-H, 3a-H diastereomers, equilibrium mixtures ofcis andtrans diastereomers were prepared which were separated and subsequently studied by¹H NMR and¹³C NMR spectroscopy. A mechanism for the isomerization of the pyrazolines is suggested, supported by a deuterium exchange at C-3a.

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Isomerisierung von einigen substituierten 4,5-Dihydropyrazolen

Zusammenfassung Die Isomerisierung einiger tricyclischer 2-Pyrazoline mit N-Carbamoyl-, N-Thiocarbamoyl-und N-Phenyl-substituenten unter saurer und basischer Katalyse wurde untersucht. Ausgehend von dencis odertrans 3-H,3a-H-Diastereomeren wurdencis- undtrans Gleichgewichtsgemische gewonnen, die getrennt und durch¹H- und¹³C-NMR-Spektroskopie untersucht wurden. Ein Mechanismus für die Isomerisierung von Pyrazolinen wird vorgeschlagen, der durch den Deuteriumaustausch in Position 3a-C unterstützt wird.

     

杂氮硅三环类化合物结构的固体NMR实验研究

采用固体NMR实验方法研究了取代的三个杂氮硅三环羧酸化合物的结构,针对实验结果讨论了环上取代对化合物构型和配键的影响,以及硅和氮化学位移对环上取代的反映。     

13C and1H NMR spectra of substituted dihydropyrroles prepared by the reaction of 2-aminooxazoles and maleimide

Substituted dihydropyrroles were characterized by¹³C and¹H NMR spectra. The spectral patterns of these compounds and reversible hydrogen—deuterium exchange are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 697–700, April, 2000.     

Quinone imines and aminophenols as precursors of new heterocycles

Cyclization of substituted quinone imines and diazabutadiene derivatives of aminophenols affords 4aH-phenoxazine or 4H-1,4-benzoxazine derivatives, which are finally transformed into the following fused heterocycles: the stable 1,4,6,8-tetra(tert-butyl)phenoxazin-10-yl radical and 7a,14a,15a, 15b-tetrahydro-14,16-dioxa-5,9-diaza-8,15-ethenohexaphene and 5a,6,11a, 12-tetrahydro[1,4]benzoxazino[3,2-b][1,4]benzoxazine derivatives. The influence of the substituents on the pathways of the reactions of intermediate benzoxazines and phenoxazines, such as oxidation, [2+4] dimerization, and the closure of the second ring, was studied. The structures of the fused heterocycles were determined by X-ray diffraction, NMR spectroscopy, and ESR. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2491–2496, November, 2005.     

NMR analysis of a series of substituted pyrazolo[3,4-d] pyrimidines-4-amines

A series of 21 substituted pyrazolo[3,4-d]pyrimidines-4-amines were studied by (1)H and (13)C NMR. The application of two-dimensional techniques, HMQC and HMBC, allowed the complete assignment of the spectra for all the compounds.     

N-methyI-N-(triethoxysilylmethyl) andN-methyl-N-(silatran-1-ylmethyl) substituted glycine and alanine

Organosilicon derivatives of glycine, - and -alanine, and -methylalanine were prepared by the reaction of methyl esters of - and -halocarboxylic acids withN-methylaminomethyltriethoxysilane in the presence of triethylamine. The compounds synthesized were converted into the correspondingN-silatran-l-ylmethyl derivatives. Trimethylsilyliodoacetate reacts withN-methylaminomethyltrietoxysilane to give 2,2-diethoxy4-methyl-1-oxa-4-aza-2-silacyclohexane-6-one. Its reaction with triethanolamine leads toN-methyl-N-(silatran-l-ylmethyl)glycine.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 341–343, February, 1995.     

Study of the mechanism of redox transformations of sterically hindered <Emphasis Type="Italic">N</Emphasis>-aryl-<Emphasis Type="Italic">o</Emphasis>-iminoquinones

The mechanisms of redox transformations of sterically hindered [¹IBQ]-[³IBQ], 9,10-iminophenanthraquinone [⁴IFQ], and o-aminophenol [⁵AP] have been studied by cyclic voltammetry. It has been shown that the reduction process in tetrahydrofuran consists of two consecutive reversible steps leading to the formation of a radical anion and a dianion. In the case of acetonitrile, only the first redox process is detected, which involves the steps of protonation and electron addition resulting in the formation of a monoanion. Quantum-chemical calculations indicate a lower degree of participation of the six-membered nonaromatic carbon ring in the spin density delocalization in the o-iminosemiquinonate radical anions as compared to o-benzosemiquinonate radical anions. The oxidation of iminoquinones results in the formation of an unstable radical cation, which undergoes further chemical transformations. An increase in the acidity of a medium leads to the formation of protonated forms with the reduction potential being shifted anodically. The introduction of screening groups makes it possible to suppress side reactions of hydrolysis and cyclization of oxidized o-aminophenol [⁵AP] forms. Therefore, the major product of complete electrolysis is o-iminobenzoquinone [²IBQ].     

The structure of products of reaction ofo-phenylenedioxytrichlorophosphorane with arylacetylenes

The products of reaction ofo-phenylenedioxytrichlorophosphorane with arylacetylenes were identified as 4-aryl-2-chloro-2-oxo-5,6-(4-chlorobenzo)phosphorin-3-enes using¹H,¹³C,³¹P NMR, and IR spectroscopy and high-resolution mass spectrometry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 368–370, February, 1997.     

A regioselective synthesis of aryl substituted arylacetates through ring transformation by ethyl levulinate

A regioselective synthesis of sterically hindered ethyl arylacetates in one step through ring transformation of suitably functionalized 6-aryl-3,4-disubstituted-2H-pyran-2-ones with ethyl levulinate at room temperature in excellent yields is described.     

N′-(取代嘧啶-2-基)-N-菊酰硫脲的合成与生物活性研究

采用活性基团拼接法, 将第一菊酸构型中的最高活性组分(＋)-反式菊酸以及二氯菊酸引入到含取代嘧啶环的酰基硫脲结构中, 合成了5个未见文献报道的N′-(取代嘧啶-2-基)-N-(＋)-反式菊酰硫脲衍生物(3a～3e)和3个均未见文献报道的N′-(取代嘧啶-2-基)-N-二氯菊酰硫脲(3f～3h), 结构经元素分析、IR和¹H NMR得到确证. 初步的生物活性测试结果表明: 大部分化合物具有较好的杀菌活性, 有的化合物兼具除草和杀菌活性, 有的化合物兼具杀虫和杀菌活性.     

Combined application of 2D NMR correlation methods and ab initio chemical shift calculations to the structure determination of new heterocyclic compounds

The combined use of 2D NMR correlation methods and ab initio chemical shift calculations is efficient and, in some cases, virtually the only way to determine the structures of new organic compounds. This approach enabled us to establish the structure of the major unusual product of the three-component reaction of imidazo[1,5-a]quinoxalin-4-one, bis(2-chloroethyl)amine hydrochloride, and potassium carbonate in DMF. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2172–2179, December, 2006. Dedicated to Professor A. V. Il’yasov on the occasion of his 70th birthday.     

Electrocatalytic chain transformation of salicylaldehyde and CH acids into substituted 4<Emphasis Type="Italic">H</Emphasis>-chromenes

Electrochemically initiated catalytic chain transformation of salicylaldehydes and CH acids containing the cyano group in an ethanolic solution in an undivided cell produced substituted 4H-chromenes in 85–95% yields. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 582–587, March, 2008.     

19F NMR study ofcis- andtrans- effects of substituted triphenylphosphine ligands intrans-(4-fluorophenyl)triarylphosphine-tri(4-fluorophenyl)phosphineplatinum 4-fluorothiophenoxides

A number of compounds of the type oftrans-4-FC₆H₄Pt(PAr₃)₂SC₆H₄F-4, where Ar is a substituted phenyl group, have been prepared starting from the corresponding chlorides. By exchange reactions oftrans-4-FC₆H₄Pt[P(C₆H₄F-4)₃]₂SC₆H₄F-4 with the above-mentioned compounds or Ar₃P,trans-4-FC₆H₄Pt[P(C₆H₄F-4)₃][PAr₃]SC₆H₄F-4 have been generated in solution. For the latter compounds, the effect of Ar₃P oncis- andtrans-ligands has been studied by the¹⁹F NMR technique. It has been shown that thecis- andtrans-effects of Ar₃P run parallel and are well described by pK _a values and ionization potentials of the unshared electron pair in Ar₃P, as well as by ⁰ constants of the aryl groups.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1359–1363, July. 1995.