Phosphorus oxybromide → 1-Bromo-6-(2-ethyl-6-methyl-phenoxy)-4-hydroxy-isoquinoline-3-carboxylic acid butyl ester

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Reaction Steps

A mixture of 6-(2-Ethyl-6-methyl-phenoxy)-1,4-dihydroxy-isoquinoline-3-carboxylic acid butyl ester (2.83 mmol, 1.12 g), POBr3 (11 mmol, 3.19 g), MeCN (20 mL) was refluxed gently with stirring for 1 h before it was concentrated in vacuo. The residue was dissolved in CHCl3 (50 mL). Water (10 mL) and subsequently small portions of NaHCO3 (6 g) were added with stirring. The mixture was stirred for 30 min at ambient temperature before it was filtered through a pad of celite. The filtrate was dried over MgSO4. Concentration and purification of the residue by flash column chromatography on silica gel using CH2Cl2 as the eluent gave the title compound as a tan oil (450 mg); MS-(+)-ion: M+1, 79Br/81Br=458.4 and 460.6.

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