[3+2] Cycloaddition of diaryldiazomethanes with (E)-3,3,3-trichloro-1-nitroprop-1-ene: An experimental, theoretical and structural study

Abstract The participation of different diaryldiazomethanes as three-atom components (TACs) in [3 + 2] cycloaddition reactions with (E)-3,3,3-trichloro-1-nitroprop-1-ene was analysed. All of the examined reactions occur with full regioselectivity, leading to respective 3,3-diaryl-4-trichloromethyl-5-nitro-Δ1-pyrazolines. Contrary to other known nitro-Δ1-pyrazolines, these products do not decompose via the N2- and/or HNO2 extrusion. At the same time, their spontaneous dehydrochlorination process was unexpectedly observed. This is clearly a rare case of the HCl-elimination from trichloromethylated heterocycles which running under mild conditions. Moreover, the [3 + 2] cycloaddition reaction between diphenyldiazomethane and (E)-3,3,3-trichloro-1-nitroprop-1-ene has been theoretically studied using Molecular Electron Density Theory.