Preparation and reactions of some substituted pyrazine di-N-oxides

Abstract

2,5-Dichloro-3,6-dimethylpyrazine is readily oxidised by trifluoroperacetic acid to the di-N-oxide, in which only one chlorine atom is easily hydrolysed by acid or base; however both chlorine atoms can be displaced by alkoxide ions. Treatment of the dibenzyloxy-derivative with acid gives 1,5-dihydroxy-3,6-dimethylpyrazin-2(1H)-one 4-oxide, related to pulcherriminic acid. Oxidation of 2-chloro-3,6-dimethylpyrazine 4-oxide with trifluoroperacetic acid gives the di-N-oxide, which can react further, by oxidative deoxygenation, to give 2-chloro-3,6-dimethylpyrazine 1 -oxide.