1,2,4-Triazines. II. New Zwitterionic Methylation Products of Some 1,2,4-Triazin-5(2H)-Ones and Their Identification by Carbon-13 Nuclear Magnetic Resonance Spectroscopy

Abstract

The methylation of various 3-and 6-substituted 1,2,4-triazin-5(2H)-one derivatives yield new zwitterionic N1 methylation products in addition to the previously reported 2-, 4- and Omethyl isomers. Specifically, 3-phenyl-1,2,4-triazin-5(2H)-one and its 6-methyl and 6-phenyl derivatives gave 1-methyl-3-phenyl-1,2,4-triazinium-5-olate, 1,6-dimethyl-3-phenyl-1,2,4-triazinium-5-olate and l1methyl-3,6-diphenyl-1,2,4-triazinium-5-olate, respectively, upon methylation. A new hindered derivative, 3,6-di-t-butyl-l,2,4-triazin-5(2H)-one, did not yield a zwitterion upon methylation but instead gave the 2- and Omethyl isomers. In all cases, carbon-13 nuclear magnetic resonance spectroscopy employing both proton-coupled and -decoupled spectra was used to identify the sites of methylation.