To a solution of Ethyl 3,5-dibromo-4-(dimethylamino)thiophene-2-carboxylate (compound 34c, 3.0 g, 8.40 mmol) in a mixture of toluene:ethanol (5 ml:30 ml) was added (4-chlorophenyl)boronic acid [1.44 g, 9.24 mmol] and potassium carbonate (2.32 g, 16.80 mmol) at 25° C. Nitrogen gas was bubbled through the reaction mixture for 15 minutes. To the reaction mixture was then added tetrakis(triphenylphosphine)palladium(0) (0.48 g, 0.42 mmol) under nitrogen atmosphere and the reaction mixture was heated at about 95 to 100° C. for 3 hr under stirring. The progress of the reaction was monitored by TLC. The reaction mixture was then cooled to 25° C. and filtered through celite, the celite cake was then washed with ethyl acetate (50 ml). The filtrate so obtained was then concentrated under reduced pressure to obtain a crude product, which was then purified by flash column chromatography using 12% ethyl acetate in hexanes as an eluent to obtain the title compound (2.5 g, 76.56%).
