Regioselective synthesis of novel antibacterial pyrazole-benzofuran hybrids: 2D NMR spectroscopy studies and molecular docking

The acetyl derivative bearing benzofuran moiety, its enaminone and different hydrazines are used as synthons for the regioselective synthesis of substituted pyrazoles. Their structures were elucidated by 2D H-1-H-1 COSY, H-1-H-1 NOESY and H-1-C-13 HMBC NMR, spectrometry. Also, a series of novel pyrazolebenzofuran hybrids have been synthesized by the regioselective cycloaddition of enaminone to hydrazonyl chlorides. The series was elucidated by IR, H-1-NMR, C-13-NMR, 2D(1)H-H-1 COSY, H-1-H-1 NOESY and H-1-C-13 HMBC NMR spectrometry as well as elemental analyses. The series was subjected for testing their antimicrobial activities. Pyrazole derivative 12c showed the highest inhibitory activity against all different bacterial strains with minimum inhibitory concentration values of 7.81, 15.6, 15.6 and 3.91 mu g/mL against Staphylococcus aureus, Streptococcus mutans, Escherichia coli and Klebsiella pneumonia, respectively, as compared to standard drugs for gram-positive and negative bacterial strains. The structure-activity relationship studies and molecular docking were performed to explain the inhibitory activities. (C) 2019 Elsevier B.V. All rights reserved.