2-(4-Chlorophenyl)ethyl chloride → 1-[2-(4-Chloro-phenyl)-ethyl]-2-(1-isopropyl-piperidin-4-ylcarbamoyl)-1H-benzoimidazole-5-carboxylic acid methyl ester

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1-[2-(4-Chloro-phenyl)-ethyl]-2-(1-isopropyl-piperidin-4-ylcarbamoyl)-1H-benzoimidazole-5-carboxylic acid methyl ester and 3-[2-(4-Chloro-phenyl)-ethyl]-2-(1-isopropyl-piperidin-4-ylcarbamoyl)-3H-benzoimidazole-5-carboxylic acid methyl ester were prepared by a procedure according to example 5 iii) starting from 300 mg (0.87 mmol) 2-(1-Isopropyl-piperidin-4-ylcarbamoyl)-1H-benzoimidazole-5-carboxylic acid methyl ester and 365.9 mg (2.09 mmol) 1-chloro-4-(2-chloro-ethyl)-benzene. Since 1-chloro-4-(2-chloro-ethyl)-benzene is less reactive the reaction time had to be extended to 10 h. Preparative RP-HPLC (CH3CN/H2O gradient+0.05% formic acid) gave a 4:3 mixture of both isomers described in the title. These isomers could be separated by NP-HPLC using a chiral stationary phase and a mixture of heptane, ethanol and methanol as solvent. Structural assignment of both isomers was achieved by NOE-spectroscopy.

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