Abstract:As a consequence of one-pot, three-component reaction of trans-2-benzoyl-3-(4-nitrophenyl)aziridine with 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde and ammonium acetate, 2-(5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)-6-(4-nitrophenyl)-4-phenyl-1,3-diazabicyclo[3.1.0]hex-3-ene was achieved in good yield. The desired photochromic compound display interesting photochromic behavior in the crystalline and solution phase. The structure of the newly synthesized photochromic compound was characterized by elemental analysis, 1 H-NMR, 13 C-NMR and UV-Visible spectral data.