(Z)-1-(3-Amino-4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-ethene (1.92 g, 6.1 mmols), 2.58 g (7.3 mmols) of Fmoc-L-Leu, 1.5 g (7.3 mmols) of DCC and 1.1 g (7.3 mmols) of HOBtH2O were dissolved in 40 ml of N,N-dimethylformamide, and the mixture was reacted at room temperature for 12 hours. The reaction mixture was diluted with ethyl acetate, then filtered and concentrated. The product was purified through silica-gel column chromatography (mixture of ethyl acetate and hexane at a ratio by volume of 1:2) to produce 3.05 g of the final product in a yield of 76.9%.
