A mixture of 2,6-dimethoxy-4-(tert-butyl-diphenylsilyloxy)benzeneboronic acid (3 g), N-(2,6-dichlorobenzoyl)-4-bromo-L-phenylalanine ethyl ester (0.8 g), Pd(PPh3)4 (1 g) and K2CO3 (2.1 g) in DME/H2O (20 mL/0.5 mL) was heated at 80° C. for 6 hour under N2. The mixture was diluted with EtOAc and washed with water, dried and evaporated. The residue was dissolved in EtOAc and the solution was filtered through a silica gel column and evaporated. The residue was dissolved in THF, and TBAF (1.6 M in THF, 4 ml) was added. The mixture was stirred at room temperature for 1 hour, diluted with water and extracted with EtOAc. The extract was washed with water, dried and evaporated. The residue was purified by flash column chromatography (silica gel; eluent: EtOAc/hexane 1/2) to yield 0.5 g of N-(2,6-dichlorobenzoyl)-4-(2,6-dimethoxy-4-hydroxyphenyl)-L-phenylalanine ethyl ester. ESMS m/z: 490 (MH+).
