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ord-0b0035404bff4099a5e08c9ac05b0329
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Objective: Test of scope in the coupling of ester substituted aminooxazole To an oven-dried microwave vial was added ethyl 2-aminooxazole-5-carboxylate (156 mg, 1.00 mmol), 6-chloropyrazine-2-carbonitrile (139 mg, 1.00 mmol), cesium carbonate (651 mg, 2.00 mmol), TRIS(DIBENZYLIDENEACETONE)DIPALLADIUM(0) (22.87 mg, 0.02 mmol) and (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (43.4 mg, 0.075 mmol) and the vial was capped and purged with nitrogen. dioxane (4 mL) (degassed) was added and the reaction mixture was heated to 160 °C for 1 h under microwave irradiation. DCM (20 mL) was added to the crude reaction mixture together with silica (2 g) and the solvent was removed under reduced pressure. The resulting residue was added to a dry-load tube prior to chromatography.The crude product was purified by flash silica chromatography, elution gradient 0 to 1% methanolic ammonia in DCM.. Pure fractions were evaporated to dryness to afford ethyl 2-(6-cyanopyrazin-2-ylamino)oxazole-5-carboxylate (121 mg, 46.7 %) as a cream solid. Conclusion: The desired product was formed in moderate yield purity.