Abstract
Studies of the internal rotation about the C—N bond of the dimethylaminomethylene (DMAM) group of DMAM-adenosine, 1, DMAM-guanosine, 2, and DMAM-cytidine, 3, was determined by high-resolution 1H NMR spectroscopy. Arrhenius plots (ln k = ln A − Ea/RT) were used to determine the barriers to internal rotation, Ea, of the compounds. They were found to be 58.0 ± 2.4 kJ mol−1, 71.2 ± 1.4 kJ mol−1, and 62.8 ± 2.4 kJ mol−1 for 1, 2, and 3, respectively. At the same time the coalescence temperatures, tc, for the compounds were determined and found to be 93.5 °C for 1, 124.7 °C for 2, and 119.6 °C for 3 in DMSO. In D2O, compound 1 was found to have a tc of 104.5 °C. The compound decomposed so rapidly at this temperature that the barrier to internal rotation could not be determined. The results indicate that the oxo function in the nucleobase has a considerable effect on the barrier to internal rotation and coalescence temperature.
Publisher
Canadian Science Publishing
Subject
Organic Chemistry,General Chemistry,Catalysis
Cited by
1 articles.
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