A facile and efficient method was described for oxidation of some 3,5-diacyl or 3,5-diester 1,4-dihydropyridines using H 2 O 2 in the presence of superparamagnetic core-shell metal-organic framework Fe 3 O 4 @Ni-MOF.
The Fe 3 O 4 @Ni-MOF has been obtained byStep-by-Step method in which magnetic Fe 3 O 4 magnetic nanoparticles were coated with Ni-MOF using a mercaptoacetic acid linker. The synthesized catalyst was characterized using thermogravimetric analysis, FT-IR spectroscopy, powder X-ray diffraction, field emission scanning electron microscopy and energy-dispersive X-ray analysis. The novel superparamagnetic core-shell metal-organic framework Fe 3 O 4 @Ni-MOF revealed high efficiency for oxidation of various 1,4-dihydropyridines using hydrogen peroxide. The Box-Behnken design matrix and the response surface method were applied to investigate the optimization of the reaction conditions. The conditions for optimal reaction yield and time were: amount of catalyst ≈17 mmol, temperature ≈78 C and amount of hydrogen peroxide ≈ 1 ml. A variety of 3,5-diacyl or 3,5-diester 1,4-dihydropyridines with different substituted functional groups have been converted to corresponding pyridines with good to excellent isolated yields using H 2 O 2 and Fe 3 O 4 @Ni-MOF. The catalyst was reused up to five times for the oxidation of 1,4-dihydropyridines without a significant loss in catalytic activity. The short reaction times, simplicity of method, good to excellent yields and reusability of catalyst were some advantages of the proposed procedure.