A suspension of intermediate D4 (0.46 g, 1.9 mmol), intermediate D7 (0.69 g, 2.28 mmol) and tetrakis(triphenylphosphine)palladium(0) (0.21 g, 0.19 mmol) in a mixture of dioxane (4 ml) and saturated aqueous sodium carbonate (4 ml) was heated at 150° C. for 10 minutes, under microwave irradiation. The crude was filtered over diatomaceous earth and washed with EtOAc. The organic layer was separated and washed with brine, dried (Na2SO4) and the solvent evaporated in vacuo. The crude product was purified by column chromatography (silica gel; DCM/EtOAc 8:2 and finally EtOAc as eluent). The desired fractions were collected and evaporated in vacuo to yield D8 (0.64 g, 95%) as a yellow solid.
