To a mixture of 2,6-dichloro-1-hydroxymethyl-3-[N-methyl-N-[4-(methylcarbamoyl)cinnamoylglycyl]amino]benzene (8.10 g) in dichloromethane (81 ml) was added triphenylphosphine (5.66 g) and carbon tetrabromide (8.95 g) at 0° C. After 15 minutes the reaction mixture was stirred at ambient temperature for 3 hours. To the mixture was added triphenyiphosphine (1.42 g) and carbon tetrabromide (2.39 g) and stirred for another 2 hours. The reaction mixture was washed with saturated sodium hydrogen carbonate, water and brine. After dried over anhydrous magnesium sulfate, the mixture was filtered and evaporated in vacuo. The residue was purified by flash column chromatography eluting with dichloromethane:ethyl acetate (1:1, V/V) and dichloromethane:methanol (20:1, V/V) followed by crystallizing from ethyl acetate to give 2,6-dichloro-3-[N-methyl-N-[4-(methylcarbamoyl)cinnamoylglycyl)amino]benzyl bromide (6.40 g) as pale yellow crystals.
