Phosphorus oxychloride → 3-(5-tert-Butyl-isoxazol-3-ylcarbamoyl)-morpholine-4-carboxylic acid tert-butyl ester

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Reaction Steps

To a cold (0° C.) solution of morpholine-3,4-dicarboxylic acid 4-tert-butyl ester (100 mg; 0.432 mmol) and 3-amino-5-t-butylisoxazole (58.9 mg; 0.42 mmol) in anhydrous pyridine (1.2 mL) is added phosphorous oxychloride (0.039 mL; 0.432 mmol). The reaction mixture is left stirring at room temperature for 1 hour. After this time, the reaction mixture is quenched with saturated NH4Cl aqueous solution and extracted with ethyl acetate twice. The organics are combined and washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure. Purification by flash chromatography on silica gel using methanol/methylene chloride provides the title compound, m/z 354 [M+H+].

Provenance & Evidence