Publication Date:
2013-07-30
Description:
We report a preparation of new 6-substituted-5,6-dihydrobenzo[ c ]phenanthridines by the reaction of azoles with quaternary benzo[ c ]phenanthridine alkaloids sanguinarine and chelerythrine. The prepared compounds have been characterized by NMR spectroscopy, mass spectrometry , and single-crystal X-ray diffraction. Conformational behaviors of carbazole derivatives in solution have been investigated by low-temperature NMR experiments. Barriers to rotation around newly formed C6–N bonds were determined to be 12–13 kcal/mol. Quantum chemical calculations have been used to reproduce the experimental observations. Large structural effects on several 1 H NMR resonances were observed experimentally, analyzed by Density Functional Theory (DFT) calculations at B3LYP/6-311+G(d,p)/PCM level, and interpreted by ring-current effects of the benzo[ c ]phenanthridine and carbazole units. Copyright © 2013 John Wiley & Sons, Ltd. Barrier to rotation around C–N bond was determined experimentally by low-temperature 1 H NMR spectroscopy and calculated by using density functional theory (B3LYP/6-311+G(d,p)). Structural effects on selected 1 H NMR resonances are rationalized by ring currents of benzo[ c ]phenanthridine and carbazole moieties.
Print ISSN:
0894-3230
Electronic ISSN:
1099-1395
Topics:
Chemistry and Pharmacology
,
Physics
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