2,4-Dichloropyridine → Ethyl 2-[(4-chloro-2-pyridinyl)amino]-1,3-oxazole-5-carboxylate

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Objective: Repeat of optimised conditions found in process research and devellopment screen for an isolated yield. An activated catalyst solution was prepared by adding TRIS(DIBENZYLIDENEACETONE)DIPALLADIUM(0) (61.3 mg, 0.07 mmol) and (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (77 mg, 0.13 mmol) to an oven-dried microwave vial. The vial was then capped and purged with nitrogen and anisole (1 mL) was added. The solution was stirred at 50°C for 40 mins, then 90°C for 15 mins (activated catalyst solution, Soln. 1). To another oven-dried microwave vial was added potassium carbonate (126 mg, 0.91 mmol), ethyl 2-aminooxazole-5-carboxylate (190 mg, 1.22 mmol) and 2,4-dichloropyridine (90 mg, 0.61 mmol) and the vial was capped and purged with nitrogen. anisole (1.35 mL) and the activated catalyst solution (0.45 mL Soln. 1 from above) were added (this corresponds to a catalyst loading of 10% Pd) and the vessel was heated to 90 °C for 16 h. LCMS of the crude reaction mixture showed the presence of a significant amount of amine starting material (Rt=0.95 min) as well as some 2,4-dichloropyridine starting material (Rt=1.75 min) together with a small amount of the desired product (Rt= 2.08). The mass corresponding to the double addition product was not observed. Conclusion: Reaction produced a small amount of the desired product but mainly starting material remained.

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