Potassium Nitrate → 8-Methoxy-2-methyl-7-nitro-2,3,4,5-tetrahydro-benzo[c]azepin-1-one

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Reaction Conditions

Reaction Steps

A mixture of 8-Methoxy-2-methyl-2,3,4,5-tetrahydro-benzo[c]azepin-1-one (227 mgs, 1.1 mmol) in MeCN/TFAA (1:1, 2 mL) was cooled to 0° C. and treated with potassium nitrate (123 mg, 1.2 mmol), then warmed to room temperature and stirred for 2 h. Poured mixture in water, extracted (EtOAc), washed with brine and the organic layer dried (MgSO4), filtered and concentrated. ISCO purification (0 to 100% EtOAc/hexane, 40 g SiO2 column) provided 8-Methoxy-2-methyl-7-nitro-2,3,4,5-tetrahydro-benzo[c]azepin-1-one (40 mgs). 1H-NMR (CDCl3) δδ 7.63 (s, 1H), 7.41 (s, 1H), 3.98 (s, 3H), 3.24 (t, J=6.3 Hz, 2H), 3.19 (s, 3H), 2.78 (t, J=7.1 Hz, 2H), 2.10-2.04 (m, 2H); LC/MS (ESI+): 250.98 (M+H). The regioisomer 8-Methoxy-2-methyl-9-nitro-2,3,4,5-tetrahydro-benzo[c]azepin-1-one was also isolated as a mixture with 8-Methoxy-2-methyl-7-nitro-2,3,4,5-tetrahydro-benzo[c]azepin-1-one. 1H-NMR (CDCl3) δ 7.22 (d, J=8.6 Hz, 1H), 7.02 (d, J=8.6 Hz, 1H), 3.90 (s, 3H), 3.32 (t, J=6.1 Hz, 2H), 3.15 (s, 3H), 2.72 (t, J=6.8 Hz, 2H), 2.06-1.99 (m, 2H); LC/MS (ESI+): 250.98 (M+H).

Provenance & Evidence