Palladium-Catalyzed Aryl Bromide Coupling

Aryl bromide pendant (0.10–0.20 mmol) (6a-f), anhydrous K₂CO₃ (3.0 eq.), meCgPPh (0.06 eq.) and Pd₂dba₃ (0.03 eq.) were added to a three-neck flask and the reaction mixture was degassed by vacuum and back-filled with nitrogen (repeated three times). 1.1 M solution of boronic acid pinacol ester intermediate 5A (1.5 eq.) in degassed 4:1 dioxane-water mixture was then added to the reaction mixture and stirred at 65 °C for 2–4 h. Reaction was monitored using TLC analysis (80% EtOAc in hexanes or 5% MeOH in CHCl₃) till the disappearance of boronic acid pinacol ester intermediate (2–4 h). The reaction mixture was diluted with ethyl acetate and washed with water. The organic layer was dried over Na₂SO_4, evaporated to dryness and purified using preparative TLC (5% MeOH in CHCl₃).