3. Low-temperature 1H and 13C NMR spectra of N-substituted 1,2,3,4-tetrahydropyrazino[1,2-a]indoles
4. Highly efficient one pot synthesis of 1-substituted 1,2,3,4-tetrahydropyrazino [1,2-a] indoles
5. Cu-nanoparticles: a chemoselective catalyst for the aza-Michael reactions of N-alkyl- and N-arylpiperazines with acrylonitrile