Synthesis, UV-Vis spectra, and Hammett correlation of some novel bis(dihydropyrrolo[3,4-c]pyrazoles)

Article abstract of DOI:10.1007/s00706-010-0351-z

Twenty-nine novel bis(dihydropyrrolo[3,4-c]pyrazole) derivatives were obtained by reacting C, N-phenyl-substituted nitrilimines generated in situ from corresponding hydrazonyl chlorides with bismaleimides. The structures were elucidated by physical and spectroscopic methods [m.p., R_f, infrared (IR),¹H nuclear magnetic resonance (NMR), ¹³C NMR, correlation spectroscopy (COSY), heteronuclear correlation (HETCOR), nuclear Overhauser effect (NOE), and high-resolution mass spectrometry (HRMS)]. Also, Hammett correlation graphs were obtained between Hammett constants σ_p and λ_max values of bis(pyrrolopyrazoles) carrying p-substituted phenyl-ring-bearing electron-withdrawing and electrondonating groups and discussed in terms of substituent effects. Springer-Verlag 2010.