First report about the use of micellar Keggin heteropolyacids as catalysts in the green multicomponent synthesis of nifedipine derivatives

VALERIA PALERMO; JEAN RODRIGUEZ; ANGEL G. SATHICQ; PATRICIA G. VÁZQUEZ; THIERRY CONSTANTIEUX; GUSTAVO P. ROMANELLI

CATALYSIS LETTERS

SPRINGER

Lugar: Berlin; Año: 2016 vol. 146 p. 1634 - 1647

1011-372X

MicellarKeggin heteropolyacid catalysts were prepared using hexadecyltrimethylammoniumbromide (cetyltrimethylammonium bromide (CTAB), 1-hexadecyl-pyridiniumchloride, and Keggin heteropolyacids H3PMo12O40 and H4PMo11VO40 as precursors. Four catalysts were prepared (PMo12C16, PMo11VC16, PMo12C16Py, and PMo11VC16Py) and characterized by P-NMR, FT-IR,XRD, SEM analysis and textural properties. The acidiccharacteristics of the catalysts were determined by potentiometric titrationwith n-butylamine. A series of bioactive 1,4-dihydropyridine derivatives such as nifedipine and nemadipine Bwere synthesized using these new materials, in a one-pot procedure in ethanol. This methodology requires a reaction time of 8 h, and a temperature of 78 °C toobtain good to excellent yields of 1,4-dihydropyridine derivatives. Themicellar Keggin catalysts are insoluble in polar media, which allows easyremoval of the reaction products without affectingtheir catalytic activity. The leaching test showed that they have an excellent stability and can be used five times as heterogeneous catalysts without appreciable loss of the catalytic activity. Using the same material,unsymmetrical 1,4-dihydropyridines such as nitrendipine can be obtained througha sequence of steps in very good yield (78%).