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ChemicalBook CAS DataBase List Ofloxacin
82419-36-1

Ofloxacin synthesis

11synthesis methods
Ofloxacin is synthesized from 2,3,4-trifluoronitrobenzene, which upon reaction with potassium hydroxide gives 2-hydroxy-3,4-difluoronitrobenzene (33.2.25). Reacting this with chloroacetone in the presence of potassium iodide and potassium carbonate gives the corresponding ether of hydroxyacetone (33.2.26). Exhaustive reduction of this compound with hydrogen over Raney nickel in one step gives the desired derivative of difluorobenzoxazine (33.2.27), bypassing, perhaps unnecessary, if not impossible, isolation stages of the amine, then the internal imine, and finally the desired product. According to the schemes of synthesis that have been repeated many times above, the secondary heterocyclic amine (33.2.27) is reacted with ethyl ethoxymethylenmalonate, and the resulting aminomethylmalonic derivative (33.2.28) cyclizes into a pyrido-benzoxazine system. However, unlike any of the cases described above where the reaction was done at high temperatures, this reaction is accomplished using polyphosphoric acid. The resulting ethyl ester of 9,10-difluoro-3-methyl-7Hpyrido (1,2,3-de)-1,4-benzoxazin-7-oxo-6-carboxylic acid undergoes hydrolysis to the corresponding acid (33.2.29). Finally, reacting this product with N-methylpiperazine replaces the fluorine atom at position C10 of the pyridobenzoxazine system, forming orloxacin (32.2.30).

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Yield:82419-36-1 95.8%

Reaction Conditions:

with potassium hydroxide in water at 60; for 6 h;Time;Solvent;

Steps:

9

3 g of starting material 9, 10-difluoro-2,3-dihydro-3-methyl-7-oxo-7H-pyridine[1,2,3,8] - [1,4] -benzoxazine-6-carboxylate, 4.58 water, 4.5 8 ^ methylpiperazine and 0.22 8 (81%)Potassium hydroxide, incubated at 60 ° C, and the reaction produced alcohol was removed during the reaction and the reaction was carried out for about 6 hours. The temperature is raised to the reflux reaction until the raw material disappears. N-methylpiperazine was completely substituted and N-methylpiperazine was recovered under reduced pressure. After acid, alkali pH adjustment, by extraction, washing, concentration and other steps. Finally, the concentrated solid was recrystallized from methanol, filtered and the mother liquor was concentrated and separated on a silica gel column (mobile phase methanol: dichloromethane = 1: 8). The solid was combined to give the ofloxacin product 3.44 g yeleld 95.8%. Compounds were determined by melting point, high molecular mass spectrometry, molecular weight, and nuclear magnetic resonance spectroscopy. The product was the same product as the product obtained in Example 7 and was anloxacin product.

References:

CN103755722,2016,B Location in patent:Paragraph 0062-0063

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