Trifluoroacetic anhydride → 1,3-Diethyl-8-methoxy-7-nitro-1,3,4,5-tetrahydro-benzo[d]azepin-2-one

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Reaction Conditions

Reaction Steps

1,3-Diethyl-8-methoxy-1,3,4,5-tetrahydro-benzo[d]azepin-2-one (564 mg, 2.28 mmol) was dissolved in 1 ml of anhydrous MeCN. The reaction was cooled to 0° C. and trifluoroacetic anhydride (3.00 mL, 21.2 mmol) and Potassium nitrate (230 mg, 2.28 mmol) were charged. The reaction was stirred for 1.5 h and then the reaction was basified with 1-2 ml of 30% NaOH solution and allowed to stir for 1 h. Pour reaction into 75 ml water and extract with 3×30 ml portions of methylene chloride. Dry the combined organic over magnesium sulfate and evaporate. Product is a yellow brown oil (625 mg). Crude material was chromatographed on a 40 g Isco column using 30-50% EtOAc in hexanes as the eluent to yield 1,3-diethyl-8-methoxy-7-nitro-1,3,4,5-tetrahydro-benzo[d]azepin-2-one (205 mg, 31%) as a tan waxy solid as a mixture of diastereomers. 1H-NMR (CDCl3) δ 7.65 (s, 1H), 6.85 (s, 1H), 4.09-3.90 (m, 5H), 3.60-3.35 (m, 3H), 3.30-3.04 (m, 2H), 2.25 (p, J=7 Hz, 1H), 1.86 (p, J=7 Hz, 1H), 1.15-1.00 (m, 6H). LC/MS (ESI+): 293 (M+H)

Provenance & Evidence