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To a 3-l round-bottom flask fitted with a stir bar and a Claisen adapter fitted with a thermocouple and a condenser blanketed with nitrogen was added terephthalic acid monomethyl ester chloride (37.3 g) and a solution of 3-amino-5-bromo-4-hydroxybenzonitrile (40 g, Step B) in dioxane (675 ml). The mixture was heated to reflux and stirred at this temperature overnight. The mixture was then cooled to room temperature and the dioxane was removed in vacuo. The flask was fitted with a Dean-Stark trap and p-toluenesulfonic acid monohydrate (35.8 g) and toluene (2.5 l) were added. The mixture was heated to reflux and stirred at this temperature overnight. The mixture was then allowed to cool, transferred to a new 5-l flask, and concentrated to a brown solid. The crude product was triturated with methanol to provide 55.5 g (83%) of the title compound. 1H NMR (500 MHz, DMSO-d6): δ 8.50 (s, 1H), 8.34 (d, J=8.0 Hz, 2H), 8.29 (s, 1H), 8.19 (d, J=8.0 Hz, 2H), 3.91 (s, 3H).

1. customTo a 3-l round-bottom flask fitted with a stir bar
2. customa Claisen adapter fitted with a thermocouple and a condenser
3. temperatureThe mixture was heated
4. temperatureto reflux
5. customthe dioxane was removed in vacuo
6. customThe flask was fitted with a Dean-Stark trap and p-toluenesulfonic acid monohydrate (35.8 g) and toluene (2.5 l)
7. additionwere added
8. temperatureThe mixture was heated
9. temperatureto reflux
10. stirringstirred at this temperature overnight
11. temperatureto cool
12. customtransferred to a new 5-l flask
13. concentrationconcentrated to a brown solid
14. customThe crude product was triturated with methanol