A mixture of 6-bromo-5-chloro-2,3-dihydrobenzo[b]furan (18) (233 mg, purity ca 60%, ca 0.6 mmol), 2-aminopyridine-5-boronic acid pinacol ester (6) (220 mg, 1 mmol), bis(ditertbutyl(4-dimethylaminophenyl)phosphine)dichloropalladium (II) (36 mg, 10% mol), Pd(PPh3)4 (58 mg) and K3PO4 (212 mg, 1 mmol) in 2 ml ACN, 2 ml dioxane, 0.5 ml H2O was bubbled with argon before heated at 85° C. for 4 h. After cooling down to r.t., the reaction mixture was taken up in EA, washed with aq. NaHCO3 and brine. Org. phase was dried over Na2SO4, concentrated and then subjected to prep HPLC purification to give 5-(5-chloro-2,3-dihydrobenzo[3,4-b]furan-6-yl)-2-pyridylamine (19) (111.8 mg, yield: 75.5%, purity>95%) as yellow solid.
