The Fischer cyclization of cyclohexanone m-tolylhydrazone under various conditions always gives a mixture of isomers (5-methyl- and 7-methyl-1,2,3,4-tetrahydrocarbazole) with predominance of the 7-methyl isomer.See [1] for communication XVIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 58–60, January, 1971. 相似文献
A series of macrocycles containing four furazan rings bonded by three azo bonds 2, 5 and 7 have been synthesized from the common precursor, 3‐amino‐3′‐nitro(azofurazan) 3 . The macrocycles closure is a result of N?N bond formation at oxidative cyclization of corresponding bis(3‐aminofurazan‐4‐yl) precursors. X‐Ray crystal structures of macrocycles 2, 2 ?AcOH, 11 and 13 are reported. 相似文献
The cyclization of diethyl ketone m-nitrophenylhydrazone under different conditions always gives a mixture of the isomeric 4-nitro-3-methyl-2-ethylindole and 6-nitro-3-methyl-2-ethylindole, generally with a certain predominance of the former. The isomer ratio depends on the nature of the catalyst used. Only 6-nitro-2,3,3-trimethylindolenine is formed in the cyclization of methyl isopropyl ketone m-nitrophenylhydrazone.See [1] for communication XXXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 37–39, January, 1973. 相似文献
A new approach is described that is able to predict the most probable metabolic sites on the basis of a statistical analysis of various metabolic transformations reported in the literature. The approach is applied to the prediction of aromatic hydroxylation sites for diverse sets of substrates. Training is performed using the aromatic hydroxylation reactions from the Metabolism database (Accelrys). Validation is carried out on heterogeneous sets of aromatic compounds reported in the Metabolite database (MDL). The average accuracy of prediction of experimentally observed hydroxylation sites estimated for 1552 substrates from Metabolite is 84.5%. The proposed approach is compared with two electronic models for P450 mediated aromatic hydroxylation: the oxenoid model using the atomic oxygen and the model using the methoxy radical as a model for the heme active oxygen species. For benzene derivatives, the proposed method is inferior to the oxenoid model and as accurate as the methoxy-radical model. For hetero- and polycyclic compounds, the oxenoid model is not applicable, and the statistical method is the most accurate. Broad applicability and high speed of calculations provide the basis for using the proposed statistical approach for high-throughput metabolism prediction in the early stages of drug discovery. 相似文献
An adiabatic formula for the contracted Hamiltonian in a reference space containing bound-state eigenfunctions of degenerate energy levels embedded in the continuum is derived. A general factorization theorem for the dynamic operatorSα(0, – ∞/λ) is proved, and the cancellation of the pole singularities in the perturbation series of the contracted Hamiltonian in adiabatic form is discussed. 相似文献
The trifluoroacetyl derivatives of alditols are convenient compounds for mass spectrometric investigation as they are easily obtainable and highly volatile. They show simple fragmentation patterns with intensive peaks in the high mass range. Trifluoroacetates of alditols may be used for detection and location of deoxy groups in the molecule. 相似文献
Among nuclides, 195mPt isomer is characterized by a number of properties that make it suitable for use in nuclear medicine. Effective ways of optimizing the Pt isomer yield at low impurity contents must be sought. The method based on double neutron capture by the 193Ir target nucleus with subsequent populating of 195mPt through β decay allows chemical isolation of the isomer. In this work, the problem is analyzed, test experiments on Ir activation with neutrons are conducted, and theoretical estimates of the 195mPt yield are presented. Full-scale model experiments on the IBR-2 reactor in Dubna should confirm the effectiveness of the method. 相似文献
The synthesis of new indoline spiropyran by the cyclocondensation in methanol revealed that the free aldehyde group of the target spiropyran is easily converted into the dimethyl acetal moiety without the addition of an acid catalyst, giving 8′-dimethoxymethyl-1,3,3-trimethylspiro[indoline-2,2′-2H-chromene]-5,6′-dicarboxylic acid as a single reaction product. The structure of this compound was confirmed by NMR spectroscopy and mass spectrometry. The molecular structure was also established by single-crystal X-ray diffraction. The Hirshfeld surfaces were generated and analyzed and intermolecular interactions in the crystal were investigated using the CrystalExplorer software package. The reverse hydrolysis reaction of dimethyl acetal to the aldehyde group proceeds under mild conditions in dimethyl sulfoxide, as shown by NMR spectroscopy.
Russian Journal of General Chemistry - Depending on the ring size in the Reformatsky reagent and the nature of substituents in arylmethylidene fragment, the reactions of Reformatsky reagents... 相似文献
A magnetic transition accompanied by a sharp decrease in magnetization has been detected in an (NdSmDy)(FeCo)B alloy at temperature T = 110 K. It is found that the sample undergoes a spin-reorientation transition accompanied with a change in the type of magnetic anisotropy. The “easy axis”-type anisotropy corresponds to high temperatures T > 110 K. A magnetic structure of the type of “the cone of easy-magnetization axes” forms at low temperatures T < 110 K. 相似文献