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

A. F. CRESPI; D. VEGA; A. K. CHATTAH; G. A. MONTI; G. Y. BULDAIN; J. M. LÁZARO MARTÍNEZ

JOURNAL OF PHYSICAL CHEMISTRY A

AMER CHEMICAL SOC

Lugar: Washington; Año: 2016 vol. 120 p. 7778 - 7785

1089-5639

The gem-diol moieties of organic compoundsare rarely isolated or even studied in the solid state. Here,liquid- and solid-state NMR, together with single-crystal X-raydiffraction studies, were used to show different strategies tofavor the gem-diol or carbonyl moieties and to isolatehemiacetal structures in formylpyridine and vitamin-B6-relatedcompounds. The change in position of the carbonyl group inpyridine compounds had a clear and direct effect on thehydration, which was enhanced by trifluoroacetic acid addition.Because of their biochemical importance, vitamin-B6-relatedcompounds were studied with emphasis on the elucidation ofthe gem-diol, cyclic hemiacetal or carbonyl structures that canbe obtained in different experimental conditions. In particular,new racemic mixtures for the cyclic hemiacetal structure from pyridoxal are reported in trifluoroacetate and hydrochloridederivatives.