0.024 g (0.03 mmol) of (PPh3)2PdCl2 is added to a solution of 0.3 g (1.13 mmol) of methyl 4-amino-6-bromo-3-chloropyridine-2-carboxylate in 20 ml of dioxane, and this mixture is stirred at RT for 30 min. In succession, 0.28 g (1.13 mmol) of 6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,3-benzoxazole, 0.47 g (3.4 mmol) of K2CO3 and 2 g (111 mmol) of H2O are then added to this mixture, which is then stirred under reflux for 6 h. The mixture is allowed to stand at RT for a further 12 h and then added to 40 ml of H2O. This mixture is extracted repeatedly with CH2Cl2, and the combined organic phase is dried over Na2SO4 and then concentrated. Purification by chromatography on silica gel using the mobile phase heptane/ethyl acetate (3/7) gives 0.1 g (29%) of product. 1H-NMR (CDCl3): δ 8.25 (s, 1H, benzoxazole), 8.15 (s, 1H, benzoxazole), 7.90, 7.80 (2d, 2H, benzoxazole), 7.20 (s, 1H, pyridine), 4.80 (bs, 2H, NH2), 4.00 (s, 3H, COOCH3).
