- Medium-sized cyclophanes. Part 56. 8-substituted 5-tert-butyl [2.2] metaparacyclophane-1,9-dienes. Preparation, X-ray diffraction study and their treatment with Lewis and protic acids
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The preparation of various 8-substituted 5-tert-butyl[2.2]metaparacyclophane-1,9-dienes 1, using the thiacyclophane method, and an X-ray diffraction study of 5-tert-butyl-8-cyano[2.2]metaparacyclophane-1,9-diene 1e are described. Lewis and protic acid-catalyzed reactions of 8-substituted [2.2]metaparacyclophane-1,9-dienes 1b-g in dichloromethane proceeded by isomerization and transannular cyclization to afford the strainless pyrenes 10 in good yields. In contrast, similar treatment of 5-tert-butyl-8-methoxy[2.2]metaparacyclophane 11 with Lewis acids in dichloromethane under the same conditions only led to recovery of the starting compound. Treatment of 8-methoxy[2.2]metaparacyclophane-1,9-diene 1d with TiCl4 in dichloromethane also led to isomerization and transannular reactions to afford 2-tert-butylpyrene 10b within 1 min in almost quantitative yield. However, the TiCl4 catalyzed reaction of an electron-poor [2.2]metaparacyclophane-1,9-diene such as 1e did not afford any product and the starting material was recovered in almost quantitative yield. These results suggest that the present novel isomerization reaction might be attributed to the bridged double bonds, which increase the strain in the molecule in comparison with the corresponding saturated [2.2]metaparacyclophane 11. The characterization and the reaction pathway of these products are also discussed.
- Yamato,Noda,Tsuzuki
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p. 721 - 727
(2007/10/03)
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- Oxidation of Aromatic Compounds. V. Oxidation of Substituted Benzonitriles and 2,4,6-Triaryl-1,3,5-Triazines in System HSO3F-PbO2
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Low-temperature oxidation of substituted benzonitriles by the system HSO3F-PbO2 proceeds with intermediate formation of cation-radicals and leads to substitution of hydrogen atoms of the methyl group or benzene ring. This reaction provides a route for preparation of chloromethylsubstituted benzonitriles, diarylmethanes, diaryls, arylfluorosulfonates and substituted benzamides with cyano groups. In the case of methyl derivatives of 2,4,6-triphenyl-1,3,5-triazine substitution of the first and then the second hydrogen atom of the same methyl group transforms it into hydroxy or chloromethyl group, or into the aldehyde function.
- Rudenko,Salfetnikova,Vasil'ev
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p. 1447 - 1470
(2007/10/03)
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- RADICAL-CATIONS OF METHYL-SUBSTITUTED BENZONITRILES
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The chemical oxidation of a series of methylated derivatives of benzonitrile in fluorosulfonic acid containing lead oxide leads to the formation of paramagnetic particles characterized by preferential localization of the unpaired electron at the C2, C3, C5, and C6 ring atoms.A computational analysis within the scope of the unrestricted Hartree-Fock method in the INDO approximation indicates that the structure of the obtained particles is described best by structures corresponding to the addition of a proton at the unshared electron pair of the nitrogen atom inthe nitrile fragment of the radical-cations.
- Rudenko, A. P.,Cheremisin, A. A.,Shchegoleva, L. N.,Detsina, A. N.,Zarubin, M. Ya.
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p. 1675 - 1684
(2007/10/02)
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