Synthesis
Step 2: Synthesis of 5-bromo-3-tert-butyl-2-hydroxybenzaldehyde (7b)
Bromine (2.95 g, 18 mmol) was slowly added to a solution of 3-tert-butyl-2-hydroxybenzaldehyde (7a, 3.0 g, 17 mmol) in acetic acid (15 mL). The reaction was carried out at room temperature and stirring was continued for 3 h after the drop was completed. The progress of the reaction was monitored by thin layer chromatography (TLC, unfolding agent ratio petroleum ether: ethyl acetate = 50:1) to confirm the completion of the reaction. The reaction mixture was quenched with water, washed with sodium bisulfite solution (50 mL) and extracted with ether. The organic layers were combined and concentrated under reduced pressure to give the crude product 5-bromo-3-tert-butyl-2-hydroxybenzaldehyde (7b, 3.2 g, 73% yield) as a white solid.
References
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[2] Advanced Synthesis and Catalysis, 2009, vol. 351, # 9, p. 1325 - 1332
[3] Inorganic Chemistry, 2017, vol. 56, # 20, p. 12357 - 12361
[4] Chemistry - A European Journal, 2006, vol. 12, # 2, p. 576 - 583
[5] European Journal of Organic Chemistry, 2001, # 24, p. 4639 - 4649
