| 摘要 |
The present invention provides a process for preparing an acid addition salt of the Z-isomer of a compound of the formula <IMAGE> (I) wherein R1 and R2 represent a lower alkyl group, or taken together with the nitrogen atom to which they are attached, form a nitrogen-containing heterocyclic group optionally containing other hetero atom or atoms; R3 and R4 represent H, a lower alkyl group, OH, a lower alkoxy group, a lower alkylcarbonyloxy group, an arylcarbonyloxy group optionally substituted with 1-2 substituents selected from lower alkyl, lower alkoxy, halo and CN on the benzene ring, a benzylcarbonyloxy group, a mono- or di(lower alkyl)aminocarbonyloxy group or a mono- or di(aryl)aminocarbonyloxy group; R5 represents a lower alkyl group or halo; and n represents 1-6, characterized in that the E-isomer of the compound of the formula (I) or its acid addition salt, singly or in admixture with the Z-isomer or its acid addition salt, is heated in an organic solvent containing hydrobromic acid.
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