To a solution of CDI (83 mg, 0.51 mmol) in EtOAc (2 mL) was added (E)-3-(6-(trifluoromethyl)pyridin-3-yl)acrylic acid (100 mg, 0.46 mmol). The resulting mixture was heated at reflux for 1 h after which HOBt (35 mg, 0.23 mmol) and 5,8-dichloro-1,2,3,4-tetrahydroisoquinoline-6,7-diol hydro bromide (145 mg, 0.46 mmol) were added. Heating at reflux was continued for 3 h before the reaction mixture was allowed to cool to rt. It was then poured into water (15 mL) and the water-phase was extracted with EtOAc (3×15 mL). Combined organics were washed with water (10 mL) and brine (10 mL) and dried (MgSO4). After filtration and evaporation, the crude was purified by column chromatography (SiO2, EtOAc:petroleum ether 50:50) to give a bright yellow solid which was purified further by precipitating the product in EtOAc via addition of petroleum ether. After decantation of the solvent and drying, the title compound (110 mg, 0.25 mmol, 55%) was obtained as a light reddish solid.
