Hydrochloric Acid → 9-Chloromethyl-7-oxo-2,3,6,7-tetrahydro[1,4]dioxino[2,3-g]quinoline-8-carboxylic acid ethyl ester

Participants

Reaction Steps

To a mixture of 1-(7-amino-2,3-dihydro-benzo[1,4]dioxin-6-yl)-2-chloro-ethanone (230 g. 1.01 mol) prepared as described in Intermediate 12, in acetonitrile (1.5 L) and triethylamine (197 mL, 1.41 mol, 1.4 eq) is added ethyl malonyl chloride (180 mL, 1.41 mol, 1.4 eq) over 0.5 h while keeping the reaction temperature less than 30° C. with an ice bath. After the addition is complete the reaction is stirred 1.5 h at room temperature. A second charge of Triethylamine (140 mL, 1.01 mol, 1.0 eq) is added and the reaction is stirred for 4.5 hours. Water (2.1 L) is added slowly followed by conc. HCl (115 mL). The slurry is stirred overnight at rt, filtered, and the solid washed with water (460 mL). The solid is then dried under high vacuum (about 1 mm Hg) at 40° C. to give 270 g (83%) 9-chloromethyl-7-oxo-2,3,6,7-tetrahydro[1,4]dioxino[2,3-g]quinoline-8-carboxylic acid ethyl ester as a yellow solid. HRMS (EI+): calc for C15H14NO5Cl: 323.0561, Found: 323.0556.

Provenance & Evidence