Phosphorus oxychloride → 4-Chloro-6,7-dimethoxyquinazoline

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Reaction Steps

A suspension of 6,7-dimethoxyquinazoline-4(3H)-one 4 (12.36 g, 60 mmol) in POCl3 (250 mL) was heated under reflux for 4 hr, when a clear solution was obtained. The POCl3 was removed under reduced pressure, and the residue was dissolved in a mixture of CH2Cl2 and aqueous Na2CO3. The organic layer was dried and the solvent removed to give 4-chloro-6,7-dimethoxyquinazoline 5 (11.2 g, 83%); m.p. 259.0-263.0° C.; 1H NMR (DMSO-d6): d 8.75(s, 1H, 2-H), 7.53(s, 1H, 5-H), 7.25(s, 1H, 8H), 3.91(s, 3H, —OCH3), 3.89(s, 3H, —OCH3); IR (KBr) umax: 2963, 2834, 1880, 1612, 1555, 1503, 1339, 1153, 962 cm−1. GC/MS m/z 224(M+, 100), 209(M+ —CH3, 9.4), 189(19.39), (69(10.55).

Provenance & Evidence