Synthesis of substituted 5-aryl-2,3-dihydropyrazine 1,4-dioxides based on condensation of N,N′-(2,3-dimethylbutane-2,3-diyl)bis(hydroxylamine) with various arylglyoxals

For the first time, a method for the synthesis of 2,3-dihydropyrazine 1,4-dioxide derivatives was devised. The presented approach is based on the reaction of N,N′-(2,3-dimethylbutane-2,3-diyl)bis(hydroxylamine) with α-ketoaldehydes. A distinctive feature of the proposed protocol is the application of sulfate of the aforementioned bis-hydroxylamine in the considered condensation. The advantages of the newly developed route are a one-step synthetic procedure involving easily available starting materials, atom economy, and simple work-up of the reaction mixture. The structure of one of the obtained products was confirmed by x-ray analysis.