Cyclization of Nitrospirobenzopyrans to Bridged Benzoxazepino[3,2-a]indoles |
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| Authors: | Neringa Kleizienė Virginė Amankavičienė Ulf Berg Carsten Schicktanz Klaus Schlothauer Algirdas Šačkus |
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| Institution: | (1) Department of Organic Chemistry, Kaunas University of Technology, Kaunas, Lithuania;(2) Organic Chemistry 1, Department of Chemistry, Lund University, Lund, Sweden;(3) Faculty of Informatics and Nature Sciences, University of Applied Nature Sciences, Merseburg, Germany |
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| Abstract: | Summary. Condensation of 1-substituted 1,2,3,9a-tetrahydro-9H-imidazo1,2-a]indol-2-ones with 5-nitrosalicylaldehyde afforded 1′-(N-monosubstituted carbamoyl)methyl]indoline nitrospirobenzopyrans.
Treatment of the latter with strong base led to the formation of a mixture of cis/trans-5a,13-methano-1,3-benzoxazepino3,2-a]indoles. Results of semiempirical calculations gave evidence that such a transformation of nitrospirobenzopyrans to bicyclic
indole derivatives could proceed via a single transition state, where the negatively charged carbon atom attacks the vinylic double bond of the spiropyran system. |
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| Keywords: | , Heterocycles, Indoles, Nitrospiropyrans, Carbanions, 5a,13-Methano-1,3-benzoxazepino[3,2-a]indoles, |
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