[CH3:1][O:2][C:3]1[CH:4]=[C:5](/[CH:13]=[CH:14]\[C:15]2[CH:20]=[CH:19][C:18]([O:21][CH3:22])=[C:17]([N+:23]([O-])=O)[CH:16]=2)[CH:6]=[C:7]([O:11][CH3:12])[C:8]=1[O:9][CH3:10].N.C([O-])=O.[NH4+]>C(#N)C.[Pd]>[CH3:22][O:21][C:18]1[CH:19]=[CH:20][C:15](/[CH:14]=[CH:13]\[C:5]2[CH:6]=[C:7]([O:11][CH3:12])[C:8]([O:9][CH3:10])=[C:3]([O:2][CH3:1])[CH:4]=2)=[CH:16][C:17]=1[NH2:23]A solution was prepared by dissolving (Z)-3,4,4′,5-tetramethoxy-3′-nitrostilbene (raw material 5) represented by the above formula (5) (5.0 g, 14.5 mmol in total including 14% of the trans-isomer) in acetonitrile (58 mL) followed by addition of 10% palladium on carbon (water-content: 51.3%, 633 mg, 0.29 mmol as palladium), aqueous ammonia (29%, 0.85 g, 14.5 mmol) and ammonium formate (95%, 2.88 g, 43.4 mmol, 300 mole % to the total of the above nitrostilbene derivative (raw material 5) and the trans-isomer thereof) to be subjected to a reaction at 30° C. for 28 hours. At the conclusion of the reaction, the catalyst and the insoluble matter were separated by filtration followed by analysis of the filtrate by HPLC. The resultant peak areas shown at a detection wavelength of 242 nm were 72%, 13%, 1.3%, 0.6%, 11% and 1.6%, respectively, for the (Z)-2-methoxy-5-[2-(3,4,5-trimethoxyphenyl)vinyl]aniline as the objective substance (objective substance 6; represented by the above formula (6)), by-products (E)-2-methoxy-5-[2-(3,4,5-trimethoxyphenyl)vinyl]aniline (by-product 7; represented by the above formula (7)), 2-methoxy-5-[2-(3,4,5-trimethoxyphenyl)ethyl]aniline (by-product 8; represented by the above formula (8)) and 2-(4-methoxy-3-nitrophenyl)-1-(3,4,5-trimethoxyphenyl)ethane (by-product 9; represented by the above formula (9)), the nitrostilbene derivative as the starting material (raw material 5), and the trans-isomer of the raw material 5. In consideration that the starting material contained 14% of the trans-isomer, it was understood that isomerization from the cis-isomer to the trans-isomer was trifling during the reaction.
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