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A solution of 2-chloro-5-methoxyaniline (5 g, 25.76 mmol) and potassium cyanate (5.22 g, 64.41 mmol) in a mixture of acetic acid (125 mL) and water (12.5 mL) was stirred at room temperature overnight. The solvent was evaporated, and the residue taken into a mixture of CH2Cl2 and an aqueous saturated solution of NaHCO3. The layers were separated, the aqueous one being extracted three times with CH2Cl2. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated. The crude material was purified by flash chromatography on silica gel (cyclohexane/EtOAc/MeOH:80/20/2) to give 2.06 g (40%) of intermediate 5.

1. customThe solvent was evaporated
2. additionthe residue taken into a mixture of CH2Cl2
3. customThe layers were separated
4. extractionthe aqueous one being extracted three times with CH2Cl2
5. washThe combined organic layers were washed with brine
6. dry with materialdried over Na2SO4
7. concentrationconcentrated
8. customThe crude material was purified by flash chromatography on silica gel (cyclohexane/EtOAc/MeOH:80/20/2)