REACTION OF DIHYDROPYRAZINE-1,4-DIOXIDES WITH ORGANOLITHIUM COMPOUNDS- SYNTHESIS OF NITROXYL RADICALS DERIVATIVES OF TETRAHYDROPYRAZINE OXIDE

Reaction of dihydropyrazine-1,4-dioxides with organolithium compounds followed by oxidation with MnO2 gives stable nitroxides of the pyrazin e series. The reaction of a pyrazine containing methylnitrone grouping s with ethylbenzoate in the presence of NaH or PhLi leads to mono- or diphenacyl derivatives, which have been shown to exist in solution as a mixture of tautomers. On treatment with hydroxylamine and subsequent oxidation the monophenacyl nitrone derivative yields a stable nitroxy l radical derived from spiroisoxazolopyrazine.