Synthesis of a Potential Impurity of Fexofenadine Hydrochloride
A potential impurity of fexofenadine hydrochloride of 4-cyclopropylcarbonyl-α,α-dimethylbenzene acetic acid methyl ester(3)was synthesized from methyl 2-[4-(4-chlorobutanoyl)phenyl]-2-methylpropanoate(2)by cyclization under the weak alkaline condition,followed by a reduction reaction using sodium borohydride to give 2-[4-(cyclopropyl(hydroxy)methyl)phenyl]-methyl-2-methylpropionate(4).Finally,2-[4-(cyclopropyl(hydroxy)methyl)phenyl]-methyl-2-methylpropionic acid(1)was prepared through hydrolysis reaction using alkali methanol solution and salification with acid.The overall yield was 53.3％and the HPLC purity was 99.4％,and the stucture was confirmed.The process is easy and safe to operate.Three impurities of the intermediate and title product was synthesized.
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