Levofloxacin, a chiral carboxycinolone, is a synthetic antibiotic with a broad spectrum effects. One of the challenges in the synthesis of this compound is efficient catalytic synthesis of their key structural intermediates (Q-acid). Several methods have been reported f
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Levofloxacin, a chiral carboxycinolone, is a synthetic antibiotic with a broad spectrum effects. One of the challenges in the synthesis of this compound is efficient catalytic synthesis of their key structural intermediates (Q-acid). Several methods have been reported for the synthesis of this active pharmaceutical ingredient in which toxic and expensive solvents have been used. In this study, focusing on the last step in the synthesis of levofloxacin using commercial Q-acid, an attempt was made using catalysts with Lewis acid character and the use of safe solvents. First, magnetic montmorillonite (MM) was synthesized and purified. The reaction of methylpiperazine with Q-acid intermediate for levofloxacin synthesis was also performed under different conditions. The best results were obtained using methylpiperazine and Q-acid with a molar ratio of 1.2:1 in the presence of catalytic amounts of MM in ethanol solvent (95%) at 70 °C for 8 h. At the end of the reaction, MM was recovered using a magnet and a simple filtration and dried for 2 h at 100° C for activation and used for 5 consecutive reactions to evaluate levofloxacin synthesis without significant decrease in efficiency. In total, taking into account factors such as raw material consumption, solvent type and simple recycling conditions, operating temperature and energy consumption, type and amount of catalyst and its recovery, solvent and catalyst biocompatibility, production of levofloxacin hemihydrate in the method presented in this study, are associated with lower cost, and its production at increased scales will have good economic benefits.
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