| 摘要 |
The present invention relates to a process for producing 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid compounds or salts thereof represented by the following formula (II): <IMAGE> (II) wherein R1, R2 and R3 independently represent hydrogen, hydroxy or lower alkoxy, and R4 represent hydrogen, lower alkyl, aryl or aralkyl, the process comprising, allowing phenylalanine compounds to react with formaldehyde or paraformaldehyde in the presence of sulfuric acid or hydrobromic acid, the phenylalanine compounds being represented by the following formula (I): <IMAGE> (I) wherein R1, R2, R3 and R4 have the same meaning as defined above.
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