Dimethylformamide → 5-Hydroxy-7,8-dimethoxy-2-oxo-2,3-dihydro-1H-benzo[b]azepine-4-carboxylic acid ethyl ester

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Reaction Conditions

Reaction Steps

A solution of 4,5-dimethoxy-2-[(4-ethoxy-1,4-dioxobutyl)amino]benzoic acid ethyl ester (5.940 g, 16 mmol) and N,N-dimethylformamide (7.5 ml) in toluene (60 ml) was added dropwise to a stirred suspension of powdered sodium hydride (80%, 2.57 g, 85.7 mmol) under argon in toluene (70 ml). After the hydrogen evolution had ceased, the mixture was stirred for 7 hours at 80° C. under argon, then cooled to 20° C. and acetic acid (5 ml) and water (40 ml) added dropwise in succession. Brine (100 ml) was added and the organic phase dried (magnesium sulphate) and evaporated to give the title compound as a white solid, (2.842 g, 55% yield), mp 218° C.; 1H-NMR (DMSO-d6, 300 MHz): δ (ppm)=12.7 (br s; 1 H), 7.96 (s; 1H), 7.3 (s; 1H), 6.49 (s; 1H), 4.32 (q; 2H), 3.95 and 3.93 (s; 6H), 3.1 (s; 2H), 1.38 (t; 3H).

Provenance & Evidence