Tributylphosphine → Ethyl 5-fluoro-4-oxo-1,4-dihydrocinnoline-3-carboxylate

Participants

Reaction Steps

A solution of tri-n-butylphosphine (8.6 g, 0.042 mol, 1.1 equiv) in anhydrous tetrahydrofuran (50 mL) was added to a tetrahydrofuran solution (150 mL) of ethyl 2-diazo-3-(2,6-difluorophenyl)-3-oxopropanoate (9.6 g, 0.038 mol). After stirring for 30 minutes at ambient temperature, the mixture was diluted with tetrahydrofuran (500 mL) and refluxed for 8 hours. The mixture was cooled to ambient temperature, concentrated in vacuo and purified by silica gel gradient chromatography (40:1; chloroform:methanol), providing the titled compound: 1H NMR (400 MHz, DMSO-d6) δ 13.85 (1H, br s), 7.78-7.75 (1H, m), 7.50-7.40 (1H, m), 7.27-7.14 (1H, m), 4.30 (2H, t, J=7.1 Hz), 1.30 (3H, t, J=7.1 Hz) ppm; low resolution mass spectrometry (APCI) m/z 237.0 [(M+H)+; calculated for C11H9FN2O3: 237.1].

Provenance & Evidence