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Title azaannulenes were synthesized starting from annulenones, and the 1H-NMR spectra are discussed in connection with tropicity of these annulenes. 相似文献
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Koichi Sakano Tsutomu Nakagawa Masahiko Iyoda Masazumi Nakagawa 《Tetrahedron letters》1981,22(28):2655-2658
Tetrakisdehydro[16]annuleno consisting of trisdehydro[16]annulene and bisdehydro[18] annulene has been synthesized. Induction of para- and diamagnetic ring currents in 16- and 18-membered rings, respectively, was clearly recognized by the 1H NMR spectroscopy. A marked suppresion of the diatropicity in the 18π moiety was observed in the same trend as observed in tetrakisdehydro[14]annuleno[16]annulene. 相似文献
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Tetrakisdehydro[14]annuleno[16]annulene consisting of an aromatic bisdehydro[14]-annulene and an antiaromatic trisdehydro[16]annulene has been synthesized. The 1H NMR parameters clearly indicate the strong paratropicity and diatropicity of the 16-membered and 14-membered rings, respectively. 相似文献
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Tetrakisdehydro[18]annuleno[20]annulene has been synthesized. The 1H NMR spectra clearly indicate the induction of dia- and paramagnetic ring currents in 18- and 20-rings, respectively. A marked suppression of the diatropicity in the 18π moiety was observed being in the same trend in other tetrakisdehydro[4n]annuleno[4n′+2]annulenes. The 1H NMR spectroscopic behavior of the annulenoannulenes is consistent with theoretical conclusion. 相似文献
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Tetrakisdehydro[14]annuleno[20]annulene consisting of an aromatic bisdehydro[14]annulene and an antiaromatic trisdehydro[20]annulene has been synthesized. The 1H NHR spectra clearly indicate the induction of para- and diamagnetic ring currents in each of the [4n]- and [4n+2]-rings, respectively. 相似文献
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Yukihiro Yoshikawa Masahiko Iyoda Masazurni Nakagawa Shinichi Nakatsuji Shuzo Akiyama 《Tetrahedron letters》1981,22(51):5209-5212
Trisdehydro[14]annuleno[16]annulene consisting of an aromatic bisdehydro[14]annulene and an antiaromatic bisdehydro[16]annulene has been synthesized. The strong paratropicity was observed in the [16]annulene moiety being comparable with that of extremely unstable parent bisdehydro[16]annulene. 相似文献
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Shigeyasu Kuroda Rie KasaiRyo Nagaya Ryuta MiyatakeYoshikazu Horino Naoko MatsumotoMitsunori Oda 《Tetrahedron letters》2011,52(13):1426-1429
3,10-Dipyrrolidinyl-4,9-methanothia[11]annulene reacts with excess dimethyl acetylenedicarboxylate (DMAD) in refluxing toluene to give ring-enlarged 6,11-methanothia[15]annulene. X-ray crystallographic analysis of the product shows two different cis,trans-dienyl parts in the ring system. Product formation possibly involves π-facial selective addition of the enamine with DMAD and torque-selective ring opening of the intermediate cyclobutenes. 相似文献
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Emanuel Vogel Ulf Kürschner Hans Schmickler Johann Lex Olof Wennerström David Tanner Ulf Norinder Carl Krüger 《Tetrahedron letters》1985,26(26):3087-3090
The molecular structure and dynamic behaviour of the bridged [4n] annulene 1,6:9,14-bismethano-[16]annulene is unravelled by NMR and X-ray investigations, combined with force field calculations. 相似文献
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Braten MN Castro C Herges R Köhler F Karney WL 《The Journal of organic chemistry》2008,73(4):1532-1535
A new global minimum for [12]annulene has been computationally located. This mono-trans minimum 5 (CCCCCT) is computed to be 1.5 kcal/mol more stable (CCSD(T)/cc-pVDZ//BHHLYP/6-311+G**) than the known tri-trans isomer 1 (CTCTCT) and 2.4 kcal/mol lower than the di-trans isomer 4 (CCTCCT), for which there is indirect evidence. The barriers for several rearrangements of 5 were all computed to be above 15 kcal/mol, indicating that direct experimental characterization of 5 should be possible. The computed barriers for the dynamic processes (including conformational automerization) coupled with computed 1H NMR shift values should aid in the future characterization of this [12]annulene isomer. 相似文献
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Hajime Ebe Tsutomu Nakagawa Masahiko Iyoda Masazumi Nakagawa 《Tetrahedron letters》1981,22(44):4441-4444
A bisdehydro[14]annuleno[c]furan, an isoannelated diatropic annulene, has been synthesized. Cyclic glycol, a precursor of the annuleno[c]furan, could be converted into bisdehydro[14]annulene derivatives under mild acidic conditions. 相似文献