Preparation of 4,4a,9,9a-tetrahydrocarbazoles and 1,3a,4,8b-tetra-hydrocyclopenta[b]indoles |
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Authors: | R R Gataullin R R Ishberdina O V Shitikova F F Minnigulov L V Spirikhin I B Abdrakhmanov |
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Institution: | (1) Institute of Organic Chemistry, Ufa Scientific Center of the Russian Academy of Sciences, Ufa, 450054;(2) Bashkir State Agricultural University, Ufa, 450001, Russia |
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Abstract: | Halocyclization of mesylates or tosylates of 2-(cycloalk-2-en-1-yl)anilines gives N-methanesulfonyl-or N-toluenesulfonyl-1-halo-1,2,3,4,4a,9a-hexahydrocarbazoles,
heating of which in DMF at 160°C or in piperidine at 110°C leads to 4,4a,9,9a-tetrahydro-3H-carbazoles. Heating N-methanesulfonyl-1-iodo-1,2,3,3a,4,8b-hexahydrocyclopentab]indole
in DMF at 180—200°C gives 1,3a,4,9b-tetrahydrocyclopentab]indole, while in the presence of an ortho-methyl substituent the
dehydroiodination reaction proceeds in piperidine at 110°C in high yield. The effect of the nature of the ortho substituent
of N-methyl-1-iodo-1,2,3,3a,4,8b-hexahydrocyclopentab]indole on the conformational equilibrium of the cyclopentane ring has
been established by 1H NMR spectroscopy.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1184–1190, August, 2006. |
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Keywords: | cyclopenta[b]indolines hexahydrocarbazoles tetrahydrocarbazoles halocyclization dehydroiodination conformation |
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