Phenylurea → 4-Hydroxy-7-(3-phenyl-ureido)-isoquinoline-3-carboxylic acid ethyl ester

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Reaction Steps

7-Bromo-4-hydroxy-isoquinoline-3-carboxylic acid ethyl ester (250 mg, 0.8443 mmol) was combined in an oven-dried flask with phenyl urea (138 mg, 1.013 mmol), cesium carbonate (550 mg, 1.69 mmol), XantPhos (49 mg, 0.0844 mmol) and tris(dibenzylideneacetone)dipalladium(0) (25 mg, 0.0422 mmol). The flask was flushed with dry nitrogen and charged with dioxane (5 mL) and the solution brought to reflux. After 44 h, the reaction was cooled and the solution partitioned between equal volumes of ethyl acetate and brine resulting in precipitation. Filtration of the solid followed by vacuum drying provided the desired urea product in 84% yield. MS ESI(+) m/e: 352.0330 (M+1).

Provenance & Evidence