PRODUCTION OF PHENYLPIPERIDINES

摘要

PROBLEM TO BE SOLVED: To provide a process for the production of a trans-4-R1-3- hydroxymethylpiperidine compound dispensing with a troublesome operation to isolate the produced tarns-isomer and free from the loss of the product in the separation process. SOLUTION: The objective trans-4-R1-3-hydroxymethylpiperidine compound (R1 is a phenyl group which may have substituents) is produced by dissolving the cis-isomer or a mixture of cis-isomer and trans-isomer of 4-R1-5-R2OOC- piperidin-2-one compound (R2OOC is an ester group forming hydroxymethyl group by reduction) in an organic solvent in the presence of a base, cooling the solution to crystallize the trans-isomer, neutralizing the reaction liquid by the addition of an acid to obtain a reaction mixture containing the trans- isomer and reacting the trans-isomer with a reducing agent in the form of the reaction mixture without isolating the trans-isomer from the mixture.