2-Amino-5-chloro-2'-fluorobenzophenone (I) is condensed with monoethyl methoxycarbonyl aminomalonate (II) and the crude product obtained (III) is deprotected by HBr to give the free amine hydrobromide (IV). This product is then cyclized in a mixture of acetic acid-sodium acetate to obtain CM-6912, which is separated by filtration and recrystallized in ethanol.