Regioselective benzylation of imidazo[1,5-a]pyridines and indoles via iodine catalyzed reaction using alcohols - An approach to crystal structure prediction, DFT studies and Hirshfeld surface analysis

Abstract

Iodine catalysed, regioselective C-1 benzylation of imidazo[1,5-a] pyridines and C-3 benzylation of indoles with diphenylmethanol has been developed. This new protocol provides an efficient protocol in the synthesis of the benzylation methodology as it targets exclusively CH bonds, even in presence of reactive NH bonds and variety of benzyl substituted indoles and imidazo[1,5-a] pyridines are synthesized with broad range of functionalities leads to the elegant formation of new CC bond under metal free conditions. This report represents a mild protocol for the synthesis of tris(heteroaryl/aryl) methanes from solid bench stable diarylmethanols. The products formed are interesting for their potential biological applications. The crystal structure of the compound 3k was determined by single crystal X-ray diffraction studies. The compound crystallized in triclinic crystal system with P-1 space group. The molecular structure is stabilized by short intermolecular interactions and intramolecular CH⋯N hydrogen bond interactions. The crystal structure also exhibits intermolecular CH⋯π, CCl⋯π and π⋯π stacking interactions. The intermolecular interactions are quantified through Hirshfeld surface analysis using fingerprint plots. The surface properties were analysed using 3D Hirshfeld surfaces. Further, the density functional theory calculations were carried to calculate the electronic properties of the molecule. The HOMO-LUMO energy gap is found to be 4.0981 eV. Finally, the chemically active sites on the molecule are identified by analysing the molecular electrostatic potential map.