Transition Metal-doped Heteropolyacid Catalysts for the Suitable Multicomponent Synthesis of Monastrol and Bioactive Related Compounds

PAULA I. VILLABRILLE, VALERIA PALERMO*, ÁNGEL G. SATHICQ, GUSTAVO P. ROMNELLI; PATRICIA G. VÁZQUEZ

CURRENT ORGANIC CHEMISTRY

BENTHAM SCIENCE PUBL LTD

Lugar: Oak Park; Año: 2015

1385-2728

Abstract: Three transition metal-doped heteropolyacid catalysts (H4PMo11VO40: PMoV, FeHPMo11VO40: FePMoV, andCuH2PMo11VO40: CuPMoV) were prepared and characterized by Fourier transform infrared spectroscopy, 31P nuclearmagnetic resonance, and diffuse reflectance spectroscopy. The acid properties of the catalysts were determined bypotentiometric titration with n-butylamine. A series of bioactive 3,4-dihydropyrimidin-2-(1H)-thiones/-ones (DHPMs)derivatives such as monastrol and piperastrol were synthesized by a one-pot procedure using the catalysts under solvent-freeconditions. The proposed methodology required short reaction time (1 h) and a temperature of 80 °C to obtain DHPMs invery good yield and high selectivity. The incorporation of V, Fe and Cu in the primary or secondary structure ofH3PMo12O40 (PMo) improved the catalytic activity of the materials. A correlation between the yields of monastrol and theacid strength or the number of acid sites of the catalysts was observed, namely, FePMoV > CuPMoV > PMoV > PMo. TheFePMoV catalyst was easily recycled and reused without appreciable loss of activity. The described synthetic method couldbe a simple, clean and environmentally friendly alternative for the preparation of bioactive substituted DHPMs.