Synthesis
General procedure for the synthesis of 4-bromo-2-iodophenol (4) from 2-iodophenol: 2-iodophenol (11 g, 50 mmol) was dissolved in a solvent mixture of dichloromethane (DCM, 200 mL) and methanol (MeOH, 100 mL). Subsequently, tetrabutylammonium tribromide (TBATB, 25.31 g, 52.5 mmol) was added in batches over 10 min. The reaction mixture was stirred at room temperature for 2 h before the reaction was quenched with 1N hydrochloric acid (HCl, 200 mL). The organic layer (DCM layer) was separated and the aqueous layer was extracted twice more with dichloromethane (DCM). All organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by fast column chromatography (silica gel, 50%-100% dichloromethane/hexane gradient elution) to afford the target product 4-bromo-2-iodophenol (10.2 g, 68% yield).
References
[1] Tetrahedron, 2015, vol. 71, # 35, p. 5946 - 5951
[2] Journal of Organic Chemistry, 2013, vol. 78, # 17, p. 8680 - 8688
[3] Organic Letters, 2015, vol. 17, # 22, p. 5666 - 5669
[4] Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences, 1931, vol. 192, p. 1037
[5] Canadian Journal of Chemistry, 1965, vol. 43, p. 650 - 658
