A mixture of 6-chloro-5-(5,5-dimethyl-1,3,2-dioxaborinan-2-yl)-1H-indole (260 mg, 1.00 mmol) and N,N-dimethylformiminium chloride (250 mg, 2.00 mmol) in dry 1,4-dioxane (5 mL) and DMF (1 mL) was sealed in a reaction vessel and stirred at room temperature for 10 minutes to give a white slurry. To the slurry was added 2M aqueous potassium carbonate (2.5 mL, 5.0 mmol), 2-(4-bromophenyl)ethanol (200 mg, 1.00 mmol) and [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (50 mg). The sealed vial was degassed and heated to 90° C. for 30 min. The cooled reaction mixture was poured into water (20 mL), and extracted with EtOAc (3×20 mL). The combined organic layers were dried and concentrated in vacuo to give 6-chloro-5-[4-(2-hydroxyethyl)phenyl]-1H-indole-3-carbaldehyde (180 mg, 68% yield) which was used in the next step without purification.
