| abstract |
1,112,723. Pyrazino-oxazines. MERCK & CO. Inc. 7 Sept., 1965 [8 July, 1965], No. 31793/67. Divided out of 1,112,721. Heading C2C. Novel compounds of the formula in which R<SP>5</SP> is a hydrogen atom or a C 1-5 alkyl or phenyl-substituted C 1-5 alkyl radical and X is a hydrogen, chlorine or bromine atom or a trifluoromethyl, C 1-5 alkyl, C 3-6 cycloalkyl, mononuclear aryl, C 1-5 alkoxy, C 1-5 alkylthio, phenyl-Bubstituted C 1-5 alkylthio, C 1-5 alkylsulphonyl, phenyl-substituted C 1-5 alkylsulphonyl or di-(C 1-5 alkyl) amino group, are prepared by heating a 3-amino-6-X-pyrazinoic acid 4-oxide with an organic acid anhydride of formula (R<SP>5</SP>CO) 2 O or, when R<SP>5</SP> is to be hydrogen, with a mixture of formic acid and acetic anhydride. |