Synthesis of p-tert-Butylcalix[4]arene Derivatives Containing Acylpyrazole Fragments

Russian Journal of General Chemistry -     

Reaction of arylidene-2-naphthylamines with the ethyl ester of (2-quinolyl)-β-oxopropionic acid

The reaction of arylidene-2-naphthylamines with the ethyl ester of (2-quinolyl)--oxopropionic acid results in the synthesis of ethyl esters of 1-(2-quinolyl)-3-arylbenzo[f]quinoline-2-carboxylic acids. All the theoretically possible intermediate reaction products were isolated: the amino esters of 2-quinoline--oxopropionic acid, the hydroxy esters of tetrahydro- and esters of dihydrobenzo[f]quinoline-2-carboxylic acid, as well as the by-products — the ethyl ester of 2-quinolyl--(R-benzylidene)--oxopropionic acid. The IR, UV, and mass spectra of the synthesized compounds are discussed.Institute of Physical Organic Chemistry, Belorussian Academy of Sciences, Minsk 220603. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1406–1410, October, 1994. Original article submitted October 5, 1994.     

Mass spectra of binuclear crown ethers

The mass-spectral analytical characteristics of binuclear crown ethers were established. The determining role of 1,5- and 1,4-C-H...O transannular interactions in the realization of rearrangement processes during fragmentation were ascertained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1615–1618, December, 1988.     

Mass spectrometry of macroheterocycles. 2. Characteristics of the fragmentation of azacrown ethers under electron impact

The fragmentation of aza-crown and diaza-crown ethers under electron impact was studied. It is shown that for the former the primary pathways of fragmentation of the molecular ions involve the intracyclic migration of a hydrogen atom and the elimination of C₂H₃O and CH₂OH particles. A characteristic feature of the diaza-crown ethers is the ejection of a divinylaminyl radical.For Communication 1 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 242–246, February, 1992.     

Stereochemistry of 2,3-disubstituted 1,3,2-dioxaborinanes

According to¹H NMR spectroscopic data, molecules of 2,4-disubstituted 1,3,2-dioxaborinanes exist in the preferred sofa conformation with equatorial alkyl groups at C₍₄₎. This conclusion has been confirmed by calculation of the optimal geometry of the ring of the cyclic boron esters by the MM2 molecular mechanics method. A. V. Bogatskii Physicochemical Institute, Ukraine National Academy of Sciences, Odessa 270080. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1574–1578, November, 1997.     

Stereochemistry of heterocycles

Twenty-eight previously unreported compounds of the 4,5-dialkyl-, 4,5,5-trialkyl-, 2,2,4-trimethyl-5-alkyl, and 2,2,4-trimethyl-5,5-dialkyl-1,3-dioxane series, including 24 individual cis and trans isomers, obtained with a purity of the order of 85–99% by fractionation of the starting mixtures of stereoisomers with total condensation columns, were synthesized. The applicability of the Cram rule, modified for compounds with complexforming groups, for the estimation of the possible configurations and conformations of the stereoisomers of the examined series was demonstrated. The cis configuration of the lowboiling stereoisomers and the trans configuration of the high-boiling stereoisomers were proved by NMR spectroscopy; the investigated compounds exist predominantly in the chair conformation. The 5-C-axial position is preferred over the 4-C-axial conformation in the examined series of compounds. The synthesis and hydrolysis of the examined 1,3-dioxanes proceed without involvement of the steric centers of the molecules, and the configurations of the corresponding diastereomeric 1,3-diols can be established on the basis of data on the configurations of the 1,3-dioxanes. The IR spectra of the stereoisomers of the examined series of compounds were studied, and the spectral characteristics of the trans and cis isomers, respectively, were found.See [30] for communication XII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 893–904, July, 1971.     

Conformation of 4,5,6-substituted 2-isopropyl-1,3,2-oxathioborinanes

The configuration and predominant conformations of 2-isopropyl-4,5,6-alkylsubstituted 1,3,2-oxathioborinanes have been studied by ¹H-NMR spectroscopy. 2,4-and 2,6-Dialkylsubstituted derivatives exist in near half-chair conformations, while 6,6-dimethyl-2-isopropyl-1,3,2-oxathioborinane exists in two energetically equivalent inverting forms. 2,5,6- and 2,4,6-Trialkylsubstituted 1,3,2-oxathioborinanes consist of mixtures of stereoisomers differing in the orientations of the alkyl groups at the C₍₆₎ and C₍₄₎ ring atoms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 242–245, February, 1990.