... Synthesis of 2(1H)-Pyrazinone 4-0xide Derivatives MITSUHIKO MANO, TAKUJI SEo, and KIN—ICHI IMAI Animal Health Products Division, Takeda Chemical Industries, Ltd ... 2722 Vol. 28 (1980) o 4 fl T ClCHZCONHR ——> < >CH=NCH2CONHR 13a—d — 14a—d ' concd. ...