Synthesis and structural investigation of some 1,4-disubstituted-2-pyrrolidinones

A series of 1,4-disubstituted 2-pyrrolidinones was synthesized by condensation of 1-aryl-4hydrazinecarbonyl-2-pyrrolidinones with aromatic aldehydes, acetone, 2-butanone, and 2,4pentane-dione. Most of the reaction products have isomers owing to the amide and azomethine structural units in their molecules. Computer molecular modeling was used to study individual features of each isomer. The structures of the synthesized compounds were unambiguously elucidated by combining IR, mass, H, and C NMR spectroscopy on the basis of the theoretical characteristics derived from molecular modeling. In this work the NMR spectra of the studied compounds 3–9 revealed a successful choice of the representative examples and good support for the explication of the peculiarities of s-cis and s-trans isomers formed in amides by the existence of E/Zconfigurations in azomethine fragments using solvents of different polarity. Data for the complete NMR assignments are presented.