Publication details

Structure and NMR properties of 6-substituted-5,6-dihydrobenzo[c]phenanthridine alkaloids

Authors

KADAM Shivaji Sambhaji MAIER Lukáš ŠOLOMEK Tomáš NEČAS Marek ŠMEJKAL Karel DOSTÁL Jiří SKLENÁŘ Vladimír MAREK Radek

Year of publication 2013
Type Article in Periodical
Magazine / Source Journal of Physical Organic Chemistry
MU Faculty or unit

Faculty of Science

Citation
Web DOI: 10.1002/poc.3175
Doi http://dx.doi.org/10.1002/poc.3175
Field Organic chemistry
Keywords 1H and 13C NMR; Nucleophilic addition; X-ray diffraction; DFT calculations; Barrier to rotation; Magnetic shielding; Conformational dependence
Attached files
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 1H NMR resonances were observed experimentally, analyzed by 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.
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