2-[2-Chloro-5-(methoxycarbonyl)phenylamino]-2-butenedioic acid diethyl ester → 8-Chloro-4-oxo-1,4-dihydro-2,5-quinolinedicarboxylic acid 2-ethyl 5-methyl ester

Participants

Reaction Conditions

Reaction Steps

A suspension of 23 (9.00 g, 25.4 mmol) in biphenyl ether (100 mL) was heated to 250° C. and stirred for 3 h. Then the reaction mixture was cooled to room temperature and purified by flash chromatography (hexanes to EtOAc) to afford a colorless oil (24, 3.88 g, 49.4%). 1H NMR (CDCl3, 300 MHz) δ 9.39 (br s, 1H), 7.75 (d, J=8.0 Hz, 1H), 7.24 (d, J=8.0 Hz, 1H), 6.96 (s, 1H), 4.54 (q, J=7.0 Hz, 2H), 4.00 (s, 3H), 1.46 (t, J=7.0 Hz, 3H).

Provenance & Evidence