A mixture of methyl 2,6-diamino-3-bromobenzoate (Intermediate 90, 1.0 g), 2-methoxycarbonyl-furan-3-boronic acid (0.980 g), tris-(dibenzylideneacetone)-dipalladium (0.188 g), tri-tert-butylphosphonium tetrafluoroborate (0.119 g) and cesium carbonate (4.0 g) in dioxane (45 mL) and water (6 mL) was de-gassed and flushed with argon. The resultant mixture was stirred at room temperature for 1 hour, then heated at 70° C. for 1 hour. The mixture was cooled, diluted with ethyl acetate and washed with water, dried (MgSO4) and filtered. The filtrate was concentrated in vacuo and the residue was purified by chromatography on silica, eluting with a mixture of ethyl acetate and pentane, with a gradient of 20-50% to give ethyl 4-(2,4-diamino-3-methoxycarbonylphenyl)-furan-3-carboxylate (0.861 g).
