Water → 7-Chloro-9-chloromethyl-2,3-dihydro[1,4]dioxino[2,3-g]quinoline-8-carboxylic acid methyl ester

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Reaction Steps

A 4-necked 5-L round-bottom flask is equipped with a mechanical stirrer and water-cooled condenser. Under nitrogen, the flask is charged with 9-chloromethyl-7-oxo-2,3,6,7-tetrahydro[1,4]dioxino[2,3-g]quinoline-8-carboxylic acid methyl ester (Intermediate 5, 360 g, 1.16 mol), as a suspension in phosphorus oxychloride (1.8 kg). The mixture is heated to reflux generating a black solution. After being heated at reflux for 20 h, the reaction mixture is allowed to cool to ambient temperature and transferred to a 25-L separatory funnel containing 18 L of ice water. After being stirred vigorously for 1.5 h, the precipitate is collected on a Buchner funnel, washed with water (3 L) and dried in vacuo. at 50° C. yielding 7-chloro-9-chloromethyl-2,3-dihydro[1,4]dioxino[2,3-g]quinoline-8-carboxylic acid methyl ester as a dark crystalline solid: mp 130-132° C. 1H NMR (CDCl3, 200 MHz) d 4.05 (s, 3H), 4.42 (s, 4H), 4.81 (s, 2H), 7.50 (s, 2H). Elemental analysis: Calculated for C14H11Cl2NO4: C, 51.24; H, 3.38; N, 4.27. Found: C, 51.10; H, 3.34; N, 4.33.

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