Formation and catalytic hydrogenation of the dimer of 1,2,3,4,5,7a-hexahydroimidazo[1,2-a]pyrazine

Reaction of diethylenetriamine with glyoxal or N,N'-dicyclohexylethylenediimine forms the novel heterocycle 1,2,3,4,5,7a-hexahydroimidazo1,2-a]pyrazine 1 (R₁ = R₂ = H) which is isolated as its dimer. Catalytic hydrogenation converts 1 into N(2-aminoethyl)piperazine in high yield.