New type of transformation of a 1,2,4-triazine ring to pyrazine derivatives

Abstract

We have discovered a new type of transformation of a triazine ring in which the l-ethyl-1,2,4-triazine cation participates. It has been established that the cation reacts at 20/sup 0/C with ortho-phenylenediamine (in methylene chloride) and 5,6-diaminopyrimidin-4-one (in 9:1 ethanol-DMF) with the formation of quinoxaline (yield 43%) and pteridin-4-one (yield 23%). This transformation is based on the susceptibility of the cation to bi-addition of nucleophiles and proceeds via cyclic adducts which are then aromatized on account of separation of 3-morpholinoamidrazone. The reaction products were identified by comparison of their melting points and spectroscopic characteristics (NMR, mass-spectra) with those of samples whose structure is definitely known.