The promoted synthesis of minoxidil by magnetic nanoparticles of cobalt ferrite(CoFe2O4) as a heterogeneous reusable catalyst

Abstract

Minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide) was primarily recognized as a drug for reducing vascular resistance to blood flow. It was later introduced as a more important medicine for topical stimulation of hair growth and baldness reverting as well as treatment of androgenic alopecia through increasing prostaglandin endoperoxide synthesis. In this study, magnetic nanoparticles (MNPs) of spinel ferrites (MFe 2 O 4 , M = Co, Ni, Fe, Cu, and Zn) via solid-state grinding procedure were prepared and then characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, and Fourier transform infrared techniques. The prepared nanoferrites were utilized as efficient and green heterogeneous catalysts for N-oxidation of 2,6-diamino-4chloro-pyrimidine with H 2 O 2 in refluxing ethanol giving 2,6-diamino-4-chloro-pyrimidine N-oxide as a starting material for the synthesis of 2,4-diamino-6-piperidinopyrimidine 3-oxide (minoxidil). Among the examined nanoferrites, CoFe 2 O 4 MNPs exhibited prominent catalytic activity giving the product in 95% yield within 60 min. Moreover, the reusability of nano-CoFe 2 O 4 was examined for 6 consecutive cycles without significant loss of catalytic activity and magnetic property.

Synthetic Approaches for Pharmacologically Active Decorated Six-Membered Diazines

“…Magnetic nanoparticles (MNPs) of CoFe 2 O 4 were prepared through a solid-state grinding procedure, in an agate mortar, where a mixture of CoCl 2 , Fe (NO 3 ) 3 Á9H 2 O, NaOH, and NaCl in a molar ratio of 1:2:8:2 was mixed, ground for 45 min at room temperature, then the excess amount of salt was removed from the reaction mixture, the obtained residue was dried in an oven at 80°C for 60 min, calcinated at 300, 500, 700, and 900°C within 80 min (20 min at each temperature) (Figure 33) [105]. A nucleophilic substitution reaction using boiling piperidine (106°C) under neat conditions with 2,6-diamino-4-chloro-pyrimidine N -oxide (169), for 120 min was then carried as step two, affording 2,4-diamino-6-piperidinopyrimidine 3-oxide (minoxidil, (171)) product in high yield (80%) and purity without requiring any further purification.…”