Gem-Diol and Hemiacetal Forms in Formylpyridine and Vitamin-B6-Related Compounds: Solid-State NMR and Single-Crystal X-ray Diffraction Studies

VEGA, DANIEL; BULDAIN, GRACIELA YOLANDA; VEGA, DANIEL; BULDAIN, GRACIELA YOLANDA; CRESPI, AYELÉN FLORENCIA; MONTI, GUSTAVO ALBERTO; CRESPI, AYELÉN FLORENCIA; MONTI, GUSTAVO ALBERTO; CHATTAH, ANA KARINA; LÁZARO-MARTÍNEZ, JUAN MANUEL; CHATTAH, ANA KARINA; LÁZARO-MARTÍNEZ, JUAN MANUEL

JOURNAL OF PHYSICAL CHEMISTRY A

AMER CHEMICAL SOC

Año: 2016 vol. 120 p. 7778 - 7785

1089-5639

The gem-diol moieties of organic compounds are rarely isolated or even studied in the solid state. Here, liquid- and solid-state NMR, together with single-crystal X-ray diffraction studies, were used to show different strategies to favor the gem-diol or carbonyl moieties and to isolate hemiacetal structures in formylpyridine and vitamin-B6-related compounds. The change in position of the carbonyl group in pyridine compounds had a clear and direct effect on the hydration, which was enhanced by trifluoroacetic acid addition. Because of their biochemical importance, vitamin-B6-related compounds were studied with emphasis on the elucidation of the gem-diol, cyclic hemiacetal or carbonyl structures that can be obtained in different experimental conditions. In particular, new racemic mixtures for the cyclic hemiacetal structure from pyridoxal are reported in trifluoroacetate and hydrochloride derivatives.