Copper catalyzed synthesis of fused benzimidazolopyrazine derivatives via tandem benzimidazole formation/annulation of δ-alkynyl aldehyde.

A novel route to synthesize the biologically active benzimidazolopyrazine core is outlined. The reaction proceeds via tandem benzimidazole formation/annulations of indole, pyrrole and aliphatic δ-alkynyl aldehydes in the presence of copper salts and green solvents with moderate to good yields.