Unusual Conformational Behavior of 3,7-Dihetera(N,N-;N,O-;N,S-) Bicyclo[3.3.1]Nonan-9-Ols Via Nmr Analysis |
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Authors: | Valentina K Yu Tynyshtyk K Iskakova Marat F Faskhutdinov Kaldybay D Praliyev Chengeer P Lee |
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Institution: | 1. Institute of Chemical Sciences, 106, Sh. Ualikhanov str., 050010, Almaty, Kazakhstan;2. Kazakh-British Technical University, 59, Tole bi, 050000, Almaty, Kazakhstan |
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Abstract: | AbstractBased upon the analysis of 1H NMR data, along with molecular modeling, it was shown that the reduction of 3,7-dihetera(N,N-; N,O-; N,S-)bicyclo3.3.1]nonan-9-ones by LiAlH4 led to a mixture of two stereoisomeric secondary alcohols with different orientations of the hydroxyl groups in one of the ring systems. Diaza derivatives in deuterochloroform exist in predominant chair-boat conformations. However, the replacement of nitrogen in one of the heterocycles by oxygen or sulfur led to stereoisomers one of which existed in chair-boat conformation and another in a chair–chair conformation. In all cases the boat conformation is stabilized by formation of an intramolecular hydrogen bond (IMHB) between a lone electron pair of the nitrogen atom and a proton on the pseudo axial hydroxyl group of the other ring. |
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Keywords: | 1Н NMR spectra 3 7-dihetera(N N- N O- N S-)bicyclo[3 3 1]nonan-9-ol conformational analysis |
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