Synthesis and characterization of a new spirooxindole grafted pyrrolidino/piperidine moiety

In this text, we synthesized and characterized a new spirooxindole grafted pyrrolidino/piperidine moieties. The new hit obtained via one-pot reaction of the chalcone based cyclohexanone with the isatin and (R)-piperidine-2-carboxylic acid in MeOH under reflux for 48 h. The compound exclusively obtained in regio-selective and diastereo-selective manner. The chemical feature of the target compound is confirmed by 1H NMR and 13C NMR spectroscopy. In addition, we reported for the first time the X-ray single crystal structure of isatin. Its molecular packing  depends mainly on strong O…H hydrogen bonds and π-π stacking interactions as well as weak H…H and H…C contacts. Using DFT calculations, isatin is a polar molecule with a net dipole moment of 5.912 Debye. Also, the calculated structure agreed very well with the experimental one. The charge distribution at the different atomic sites is calculated using NBO calculations.