Dimethyl Carbonate → 1,1-dimethylethyl 7-[3-(methyloxy)-3-oxopropanoyl]-2,3-dihydro-1,4-benzoxazepine-4(5H)-carboxylate

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Reaction Steps

A solution of 1,1-dimethylethyl 7-acetyl-2,3-dihydro-1,4-benzoxazepine-4(5H)-carboxylate (1.34 g, 4.60 mmol) in tetrahydrofuran (5 mL) was added to a suspension of sodium hydride (60% oil suspension, 0.80 g, 13.3 mmol) in tetrahydrofuran (20 mL) and the resulting mixture was stirred at room temperature for 5 minutes. Dimethyl carbonate (5 mL) was added and the resulting mixture was stirred at 65° C. for twenty minutes. Then the reaction mixture was cooled, quenched with ice (20 g) and aqueous ammonium chloride (20 mL) then extracted with ethyl acetate (3×40 mL). The combined organic extract was washed with water, then brine solution (80 mL each), dried over sodium sulfate, filtered, concentrated, and purified by silica gel chromatography (25% ethyl acetate in hexanes) to give 1,1-dimethylethyl 7-[3-(methyloxy)-3-oxopropanoyl]-2,3-dihydro-1,4-benzoxazepine-4(5H)-carboxylate (0.94 g, 59% yield). MS (EI) for C18H23NO6: 350 (MH+).

Provenance & Evidence