Metal free regioselective synthesis, crystal structure, antioxidant evaluation and Hirshfeld surface analysis of 4,5-diaryl isoxazoles

The current work describes the synthetic utilization of different alpha-aryl-beta,beta-ditosyloxy ketones as 1,3-dielectrophilic three carbon intermediates for the synthesis of scarcely under explored 4,5-diaryl isoxazoles via hitherto novel and highly efficient route. The approach was very much useful owing to (i) mild reaction conditions with operational simplicity (ii) great regioselectivity (iii) a lesser amount of reaction time. The exact chemical structures were carefully established by means of elemental analysis and different spectroscopic techniques (IR, H-1 & C-13-NMR). Antioxidant studies determine that, 4-(4-fluorophenyl)-5-(thiophen-2-yl)isoxazole (5f) exhibits fairly good potential. Single crystal XRD analysis (CCDC No. 2017597) along with 3D-hirshfeld surface analysis and their 2D-fingerprint plots are reported for 4-(4-methylphenyl)-5-(thiophen-2-yl)isoxazole (5a) (space group = P 21/c). DFT studies were used to determine the relative energies, molecular electrostatic potentials (MEPs), HOMO, LUMO energies, frontier molecular orbitals (FMOs) of reported molecules.