Reações do piridoxal com cetonas: síntese de 1,3-diidrofuro[3,4-c]piridinas e derivados

Abstract

Pyridoxal is one of the natural free forms of vitamin B6 and plays important roles in living systems. Although a low molecular weight molecule, pyridoxal has several functional groups. Therefore, it is an excellent starting material in organic synthesis. Most works explore the reactivity of carbonyl in order to prepare imines and hydrazones in order to mimic biosynthetic processes. However, a study on the Claisen-Schmidt condensation reaction between pyridoxal and ketones has not been found in the literature. In this sense, synthetic changes were made to the pyridoxal in order to obtain series of unprecedented molecules with potential applications in coordination chemistry and for the evaluation of biological activities. It were obtained from the furo[3,4-c]pyridine with yields ranging between 53 and 90% by aldol condensation reaction of Claisen Schmitd followed by oxaMichael addition among pyridoxal and enolizable ketones. In a second step, hydrazones were obtained by reacting furopyridine with different hydrazine derivatives. Finally brominations were carried out on furo[3,4-c]pyridines to prepare useful intermediates for future work involving coupling reactions. The products obtained in pure form were characterized by infrared spectroscopy, high resolution mass spectrometry, melting point, 1H NMR and 13C NMR and presented data consistent with their structures.