Boron Trichloride → Methyl 4-(3,5-dichloro-4-hydroxybenzamido)benzoate

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Reaction Steps

A solution of methyl 4-(4-(benzyloxy)-3,5-dichlorobenzamido)benzoate (4) (8.8 g, 20.5 mmol) in DCM (500 mL) was cooled to 0° C. and treated dropwise with boron trichloride (20.5 mL, 20.5 mmol, 1 M in DCM). The mixture was then allowed to stir at RT for 12 h. The mixture was cooled in an ice bath then quenched by addition of water (150 mL). The resultant mixture was partitioned between EtOAc (200 mL) and H2O (100 mL). The aqueous phase was extracted with EtOAc (2×75 mL) and the combined organic phases washed successively with water (50 mL) and brine (50 mL), then dried over MgSO4 and filtered. The solvent was removed in vacuo. The residue was crystallised from isohexane/EtOAc to afford methyl 4-(3,5-dichloro-4-hydroxybenzamido)benzoate (5) (5.81 g, 84%): m/z 338 (M−H)− (ES−). 1H NMR (400 MHz, DMSO-d6) δ: 11.06 (1H, s), 10.52 (1H, s), 8.06 (2H, s), 8.00 (2H, d), 7.95 (2H, d), 3.88 (3H, s).

Provenance & Evidence