1. 4-Bromo-3-nitroanisole (1.71 g, 7.2 mmol, 1 eq.) was dissolved in a solvent mixture of ethanol (7 mL) and water (5 mL).
2. To the above solution was added iron powder (2.00 g, 35.7 mmol, 5 eq.) and ammonium chloride (1.53 g, 28.6 mmol, 4 eq.).
3. The reaction mixture was heated to reflux for 2 hours.
4. Upon completion of the reaction, the black organic phase was extracted with ether (4 x 100 mL).
5. The organic phase was separated to give 2-bromo-5-methoxyaniline in 95% yield as a green solid.
6. 2-Bromo-5-methoxyaniline (1.50 g, 7.4 mmol, 1 eq.), the crude product, was dissolved in concentrated hydrochloric acid (7 mL) at 0 °C.
7. To the above solution was added dropwise an aqueous solution of sodium nitrite (0.5 g, 7.2 mmol, 1 eq.) (5 mL) at 0 °C.
8. Continue stirring for 5 hours at 0 °C to form the diazonium salt.
9. In another flask, treat water (8 mL) with thionyl chloride (2.2 mL, 30.3 mmol, 4 eq.) at 0 °C.
10. Stirring was continued for 1 hour at 0 °C.
11. Wash the aqueous phase with ethyl acetate (6 x 50 mL).
12. Combine the organic phases and dry with magnesium sulfate.
13. The solvent was removed under pressure and the product was purified by column chromatography (n-hexane-ethyl acetate, 5:1) to afford the target product S5 (1.50 g, 46%) as a yellow oil.
14. The Rf value of the product was 0.3 (n-hexane-ethyl acetate, 5:1), which was in agreement with the data reported in the literature.
