Ammonium formate → Methyl 3-hydroxy-5-[(4-methyl-5-oxo-2,3,4,5-tetrahydro-1,4-benzoxazepin-8-yl)oxy]benzoate

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A mixture of methyl 3-[(9-chloro-4-methyl-5-oxo-2,3,4,5-tetrahydro-1,4-benzoxazepin-8-yl)oxy]-5-[(phenylmethyl)oxy]benzoate (8.8 g, 18.8 mmol), and ammonium formate (11.87 g, 188 mmol) in methanol (190 mL) was placed under an atmosphere of argon and 10% palladium on charcoal (880 mg) added. The mixture was heated under relux for 2 hours, cooled to RT, filtered through Celite®, washed with methanol, and the filtrates evaporated in vacuo to a residue which was partitioned between water (150 mL) and ethyl acetate (200 mL). The organic layer was washed with brine, dried (MgSO4), evaporated in vacuo to a residue which was chromatographed on basic alumina, eluting with ethyl acetate then methanol, to give a solid which was crystallised from ethyl acetate and isohexane to give the desired compound (3.25 g). 1H NMR δ (CDCl3): 3.15 (s, 3H), 3.5 (t, 2H), 4.35 (t, 2H), 6.6 (dd, 1H), 6.75 (dt, 1H), 7.8 (t, 1H); m/z 344 (M+H)+

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