Synthesis
GENERAL STEPS: Resorcinol (2.0 g, 18.2 mmol) was dissolved in dioxane and the solution was cooled to 0 °C. Concentrated sulfuric acid (0.5 mL) was added slowly and dropwise at 25 °C. Subsequently, ethyl 2-chloroacetoacetate (2.8 g, 21.8 mmol) was added and the reaction mixture was heated to 60 °C and maintained at this temperature for 4 hours. After completion of the reaction, the mixture was poured into cold water, the precipitate was collected by filtration and dried under reduced pressure. Finally, the product was purified by recrystallization from methanol to give 3-chloro-7-hydroxy-4-methylcoumarin (6a) as white needle-like crystals.
References
[1] Chemistry - A European Journal, 2012, vol. 18, # 32, p. 9901 - 9910
[2] Synthesis, 2006, # 11, p. 1895 - 1897
[3] Monatshefte fur Chemie, 2008, vol. 139, # 7, p. 805 - 808
[4] European Journal of Medicinal Chemistry, 2015, vol. 95, p. 153 - 165
[5] Tetrahedron Letters, 2006, vol. 47, # 19, p. 3279 - 3281
