A mixture of the corresponding intermediate 6-(4-Bromo-phenyl)-4-(2-trimethylsilanyl-ethoxymethyl)-4,7-dihydro-1-thia-4,5-diaza-cyclopenta[a]pentalene (0.45 g, 1.0 mmol), 4-Fluoro-phenylamine (0.27 g, 2.5 mmol), Cs2CO3 (2 M, 3.0 Xantphos (58 mg, 0.1 mmol) and Pd(OAc)2 (22 mg, 0.1 mmol) in dioxane (5 mL) was heated at 100° C. for 8 hr. The solution was cooled to room temperature and extracted with ethyl acetate. The target product was purified by gravity column chromatography (20% EtOAc in hexane) to give (4-Fluoro-phenyl)-{4-[4-(2-trimethylsilanyl-ethoxymethyl)-4,7-dihydro-1-thia-4,5-diaza-cyclopenta[a]pentalen-6-yl]-phenyl}-amine as brown solid in 69% yield.
