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Mechanistic insights into chemical reactions via “in situ” NMR

19F and 1H NMR experiments were performed to study the mechanism of selected chemical reactions. In the case of the acylation (ferrocenoylation) of purine and pyrimidine nucleobases, the attention has been focused on the regioselectivity/ regiospecificity of the respective reaction. It has been shown that the reaction centre and the product isomers ratio cannot be determined from the isolated weights alone, but the analysis of ”in situ” NMR spectra is required. In the case of chlorination of the 5-fluorouracil, “in situ” NMR data has been generated under actual reaction condition [2]. The existence of the presumed chlorinated intermediates has been confirmed spectrophotometrically, which is necessary to scheme out the full reaction profile. The two cases demonstrate that the information obtained by “in situ” NMR approach may provide the answers to challenging mechanistic or kinetic studies, or may contribute to the optimization of synthetic routes.

NMR ; reaction mechanism ; acylation ; chlorination

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