title: gem-Diol and Hemiacetal Forms in Formylpyridine and Vitamin-B6-Related Compounds: Solid-State NMR and Single-Crystal X-ray Diffraction Studies.
abstract: 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.
authors.affiliation: Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires , Junín 956 (C1113AAD), CABA, Argentina.
authors.forename: Ayelén Florencia
authors.initials: AF
authors.lastname: Crespi
authors.affiliation: Departamento de Física de la Materia Condensada, Comisión Nacional de Energía Atómica , Av. Gral. Paz 1499 (1650)San Martín, Buenos Aires, Argentina.|Escuela de Ciencia y Tecnología, Universidad Nacional de General San Martín , Buenos Aires, Argentina.
authors.forename: Daniel
authors.initials: D
authors.lastname: Vega
authors.affiliation: FaMAF-Universidad Nacional de Córdoba & IFEG-CONICET , Medina Allende s/n (X5000HUA), Córdoba, Argentina.
authors.forename: Ana Karina
authors.initials: AK
authors.lastname: Chattah
authors.affiliation: FaMAF-Universidad Nacional de Córdoba & IFEG-CONICET , Medina Allende s/n (X5000HUA), Córdoba, Argentina.
authors.forename: Gustavo Alberto
authors.initials: GA
authors.lastname: Monti
authors.affiliation: Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires , Junín 956 (C1113AAD), CABA, Argentina.|CONICET , Godoy Cruz 2290 (C1425FQB), CABA, Argentina.
authors.forename: Graciela Yolanda
authors.initials: GY
authors.lastname: Buldain
authors.affiliation: Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires , Junín 956 (C1113AAD), CABA, Argentina.|IQUIFIB-CONICET , Junín 956 (C1113AAD), CABA, Argentina.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Lázaro-Martínez
mesh_terms: D060326:Chemistry Techniques, Synthetic; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry*; D011730:Pyridoxal / Q000737:chemistry; D014269:Trifluoroacetic Acid / Q000737:chemistry; D025101:Vitamin B 6 / Q000737:chemistry*
chemical_list: C538889:2-formyl pyridine; D011725:Pyridines; D011730:Pyridoxal; D025101:Vitamin B 6; D014269:Trifluoroacetic Acid