Straightforward Access to Pyrazine-(2,3)-diones Through Sequential Three-Component Reaction

A novel protocol for the assembly of polysubstituted 2,3-dioxo-1,4,5,6-tetrahydropyrazines and 2,3-dioxo-hydro-1H-cycloalkyl[b]pyrazines has been developed by the sequential three-component reaction of primary aliphatic amines, 1,2-diaza-1,3-dienes (DDs) and oxalyl chloride. This synthetic sequence proceeds by initial aza-Michael addition of the amine to the azo-ene compounds and subsequent ring closure involving the oxalyl chloride. The ready availability of the starting materials as well as the high level of practicability of the reaction and work up make this approach an attractive opportunity towards these uncommon systems.