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Archive for 26.01.2015

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J Org. Chem. 2015, 80, 18-29

M.S. Novikov, A.F. Khlebnikov, N.V. Rostovskii, S.Tcyrulnikov, A.A. Suhanova, K.V. Zavyalov, D.S. Yufit

“Pseudopericyclic 1,5- versus Pericyclic 1,4- and 1,6-Electrocyclization in Electron-Poor 4‑Aryl-2-azabuta-1,3-dienes: Indole Synthesis from 2H‑Azirines and Diazo Compounds”

J Org. Chem., 2015, 80, 18-29

DOI: 10.1021/jo501051n

Transformations of 2-azabuta-1,3-dienes, formed in Rh2(OAc)4-catalyzed reactions of diazo carbonyl compounds with 2H-azirines, dramatically depend on the nature of substituents. 4,4-Diphenyl-2-azabuta-1,3-dienes with two electron- acceptor substituents at C1 undergo thermal 1,5-cyclization to give indoles in good yields.
The increase in electronwithdrawing ability of C1-substituents facilitates the reaction that proceeds via pseudopericyclic 1,5-electrocyclization of 2- azabutadiene into 7aH-indolium ylide followed by prototropic shift. 3,4-Diphenyl-2-azabuta-1,3-dienes, resulting from reaction of 2,3-diphenyl-2H-azirine and diazo compounds, do not produce indoles via 1,5-cyclization due to the trans-configuration of the 4-Ph-group and the nitrogen, but undergo 1,4-cyclization to 2,3- dihydroazetes. 1,6-Cyclization into 2H-1,4-oxazines with participation of the oxygen of ester or amide group at C1 of corresponding 2-azabuta-1,3-dienes does not take place due to kinetic and thermodynamic reasons. Instead of this, 1,6-electrocyclization with participation of phenyl substituent at C4 of the 2-azabuta-1,3- dienes, providing isoquinoline derivatives, can occur at elevated temperatures. The DFT-calculations (mPWB1K/6-31+G(d,p)) confirm the dependence of 2-azabuta-1,3-diene transformation type on the nature of substituents.

Декабрь

В декабре выполнено 1504 заявки на сервисные измерения.

Измерено:

  • 1420 спектров 1H
  • 407 спектров 13C
  • 238 спектров DEPT
  • 23 спектра COSY
  • 11 спектров NOESY
  • 38 спектров 31Р
  • 75 спектров 19F

Выполнено 153 заявки на выполнение работ, измерения по которым в сумме заняли 1544 часа.

PCCP 2015

S. Pylaeva, C. Allolio, B. Koeppe, G.S. Denisov, H.-H. Limbach, D. Sebastiani, P.M. Tolstoy

“Proton transfer in hydrogen bonded complex caused by solvation shells fluctuations: ab initio MD study of anionic phenolate-carboxylic acid and neutral pyridine-carboxylic acid systems”

PCCP, 2015, accepted
DOI: 10.1039/C4CP04727C

Chem. Heterocycl. Compd., 2015, 50(11)

A. Ya. Bespalov, T. L. Gorchakova, A. Yu. Ivanov, M. A. Kuznetsov, L. M. Kuznetsova, A. S. Pankova, L. I. Prokopenko, M. S. Avdontceva

«Alkylation and Aminomethylation of 1,3-Dihydro-2Н-Benzimidazole-2-Thione»

Chem. Heterocycl. Compd, 2015, 50(11), ASAP
DOI: 10.1039/c4ra07840c

Alkylation of 1,3-dihydro-2Н-benzimidazole-2-thione (2-mercapto benzimidazole) with bromoethane and chloroacetic acid derivatives occurrs at the sulfur atom, leading to the corresponding 2-sulfanylbenz-imidazole derivatives. Aminomethylation of 1,3-dihydro-2Н-benzimidazole-2-thione with piperidine and 4-methylpiperidine gives reaction products at both nitrogen atoms, while reaction with morpholine gives derivative at only one nitrogen atom, which is in an equilibrium with the starting compound and bis-adduct in DMSO solution

RSC Advances, 2014

A.S. Pankova, M.A. Samartsev, I.A. Shulgin, P.R. Golubev, М.А. Кuznetsov

“Synthesis of thiazolidines via regioselective addition of unsymmetric thioureas to maleic acid derivatives”

RSC Advances, 2014, 4, 51780-51786
DOI: 10.1039/c4ra07840c

Wide range of unsymmetric thioureas has been studied in reaction with N-arylmaleimides and maleic anhydride. The regioselectivity of the addition depends not only on steric factors but on both solvent polarity and type of maleic acid derivative (imide or anhydride). The general regularities have been established providing practical guidelines to control the reaction result. The unequivocal structural assignment of all products has been done using NMR spectroscopy including 15N–1H HMBC experiments.