Method for producing 4- (cyclopropylcarbonyl) -α, α-dimethylphenylacetic acid which is a high-purity pharmaceutical intermediate

摘要

This invention relates to a novel process to obtain highly pure 4-(cyclopropylcarbonyl)-alpha,alpha-dimethylphenylacetic acid of Formula I through crystallization from a mixture of para and meta regioisomers of Formula I and II in cyclohexane, whereby the amount of undesired meta isomer, 3-(cyclopropylcarbonyl)-alpha,alpha-dimethylphenylacetic acid of Formula II is decreased to below 0.5%. The compound of Formula I is a key intermediate for the preparation of high purity terfenadine carboxylate, which is a known antihistaminic.