Dynamic NMR study of dinitrophenyl derivatives of seven-membered cyclic ketals of pyridoxine

• Published in: Magnetic resonance in chemistry 2015-10, Vol.53 (10), p.805-812
• Main Authors: Rakhmatullin, Ilfat Z., Galiullina, Leisan F., Garipov, Marsel' R., Strel'nik, Alexey D., Shtyrlin, Yurii G., Klochkov, Vladimir V.
• Format: Article
• Language: English
• Subjects: Bonding; conformational exchange; Cyclization; Derivatives; Dinitrobenzenes - chemistry; dynamic 1H NMR; Dynamic tests; Dynamics; energy barrier; Exchange; Fragmentation; ketal; Ketones - chemistry; Magnetic Resonance Spectroscopy; Molecular Structure; Nuclear magnetic resonance; Pyridoxine; Pyridoxine - chemistry; Transformations
• ISSN: 0749-1581; 1097-458X
• DOI: 10.1002/mrc.4251

Two pyridoxine derivatives containing a dinitrophenyl moiety were investigated by 1H NMR spectroscopy. Conformational dynamics in solution were studied for each compound using dynamic NMR experiments. It was shown that both compounds studied are involved into two conformational exchange processes. The first process is a transformation of the seven‐membered cycle conformation between the enantiomeric P‐twist and M‐twist forms, and the second is a rotation of the dinitrophenyl fragment of the molecules around the C–O bond. Energy barriers of both conformational transitions were determined. Copyright © 2015 John Wiley & Sons, Ltd. Conformational features and dynamic processes for dinitrophenyloxy derivatives of seven‐membered cyclic ketals of pyridoxine were studied by dynamic NMR experiments. These compounds are involved in two conformational exchange processes. One process is the rotation of the dinitrophenyl fragment around the C—O bond, and the second process is a conformational transformation of the seven‐membered cycle. Activation barriers of both conformational exchange processes were determined using line shape analysis of the NMR spectra with variation of temperature.