1-Naphthaleneboronic acid (0.52 g, 3.00 mmol) was added to a mixture of (4-bromo-2-chlorophenyl)-(5H, 11H-pyrrolo[2,1-c][1,4]benzodiazepin-10-yl)-methanone of Step A (1.27 g, 3.15 mmol) and sodium carbonate (0.53 g, 4.98 mmol) in toluene (22.5 mL), ethanol (4.5 mL) and water (9 mL). The resultant solution was purged with nitrogen for 10 minutes, then tetrakis(triphenylphosphine)palladium (0.18 g, 0.06 mmol) was added. The reaction mixture was heated to reflux for 76 hours. The solution was cooled to ambient temperature, then filtered through a pad of Celite, which was subsequently rinsed with ethyl acetate. The combined filtrate was diluted to 100 mL water/ethyl acetate (1:1). The aqueous layer was extracted with ethyl acetate, and the combined organic layer was dried over anhydrous magnesium sulfate, filtered, and evaporated to dryness to yield a brown oil. Purification by flash chromatography on silica gel eluting with hexane-ethyl acetate (5:1) resulted in a white solid which was dried under vacuum (0.62 g), m.p. 115–117.5° C.
