A mixture of tert-butyl 5-(benzyloxy)-3-bromo-1H-indole-1-carboxylate (2.011 g), 1-morpholinoprop-2-en-1-one (0.776 g), palladium acetate (31 mg), tri-o-tolylphosphine (187 mg) and triethylamine (1.14 mL) in N,N-dimethylformamide (14 mL) under nitrogen atmosphere was stirred at 100° C. overnight. The mixture was diluted with ethyl acetate and saturated ammonium chloride. The aqueous layer was extracted with ethyl acetate and the combined organic layers were dried over MgSO4, filtered and concentrated. The residue was purified by flash chromatography (80% ethyl acetate-hexane) to give the desired product.
