Under argon, 155 g (561 mmol) of the compound of Example 4A together with 133 g (617 mmol) of 2-bromo-4-nitrotoluene, 12.6 g (56.1 mmol) of palladium(II) acetate, 48.7 g (84.1 mmol) of xantphos [4,5-bis(diphenylphosphino)-9,9-dimethylxanthene] and 548 g (1683 mmol) of caesium carbonate in 3.1 liters of 1,4-dioxane were heated at reflux. After 4 h, the mixture was cooled to RT and filtered through kieselguhr, and the filtrate was concentrated on a rotary evaporator. The crude product obtained in this manner was purified by filtration with suction through silica gel (mobile phase gradient ethyl acetate/petroleum ether 4:1→100% ethyl acetate). The product fractions were combined and freed from the solvent on a rotary evaporator. Trituration with diisopropyl ether at RT, removal of the solid by filtration with suction and drying under high vacuum gave 195 g (84% of theory) of the title compound.
