Great attempts have been done for the development of novel antiviral compounds against SAR-CoV-2 to end this pandemic situation and save human society. Herewith, we have synthesized 3-substituted indole/2-substituted pyrrole 1,2dihydropyridine and azaxanthone scaffolds using simple, commercially available starting materials in a one-pot, green, and regioselective manner. Further, the regioselectivity of product formation was confirmed by various studies such as controlled experiments, density functional theory (DFT), Mulliken atomic charge, and electrostatic potential (ESP) surface. In addition, 3substituted indole 1,2-dihydropyridine was successfully converted into a biologically enriched pharmacophore scaffold, viz., indolylimidazopyridinylbenzofuran scaffold, in excellent yield. Moreover, the synthesized 3-substituted indole 1,2-dihydropyridine/ 2-substituted pyrroles were analyzed in docking studies for anti-SARS-CoV-2 properties against their main protease (M pro ) and anti-Delta plus properties against their protein of the Delta plus K417N mutant. Further, the drug-likeness prediction was analyzed by the Lipinski rule and other pharmacokinetic properties like absorption, distribution, metabolism, excretion, and toxicity using preADMET prediction. Interestingly, the docking results show that out of 20 synthesized compounds, 5 of them for M pro of SAR-CoV-2 and 9 of them for 7NX7 spike glycoprotein's A chain of Delta plus K417N show greater binding affinity when compared with remdesivir that is the first to receive FDA approval and is currently used as a potent drug for the treatment of COVID-19. These results suggest that indole/pyrrole substituted 1,2-dihydropyridine derivatives are capable of combating SARS-CoV-2 and its Delta plus mutant.
A novel strategy was developed for the synthesis of five different N-fused 1,4-dihydropyridine (1,4 DHP) scaffolds such as imidazopyridine, pyridopyrimidine, benzoimidazopyridine, thiazolopyridine and benzopyridooxazine derivatives by coupling nitroketene S,S-acetal, various nitrogen containing dinucleophiles, malanonitrile and substituted salicylaldehydes/aldehydes in the presence of InCl 3 as catalyst in water-EtOH solvent mixture under reflux condition. Furthermore, mechanism for the formation of 1,4-DHPs was explored through experimental and DFT calculations. DFT studies reveal that the reaction went through lower energy triheterocyclic intermediate than the higher energy chromenoimidazopyridine imtermediate. The attractive features of this protocol include short reaction time, easy separation of the product without chromatographic purification, simple execution with excellent yield and possibility to synthesize structurally diverse 1,4-dihydropyridine derivatives through greener approach.
ObjectivesA regioselective approach has been developed for the synthesis of benzopyranophenazine derivatives using In (OTf)3 as a catalyst in one‐pot synthesis. Further, these synthesized compounds were successfully used as organic corrosion inhibitors on mild steel in 1M H2SO4 solution.MethodsThe synthesized organic inhibitors were confirmed using NMR, and HRMS and their regioselectivity was confirmed by DFT studies using the B3LYP/6‐31G (d, p) basis set. Further, the corrosion, and inhibition efficiencies were confirmed by various methods such as weight loss technique, electrochemical impedance spectroscopy, and potentiodynamic polarization studies.ResultsThe two synthesized compounds MBPPand BBPP show excellent corrosion inhibition properties than the previously reported organic inhibitors, especially, the electron‐donating nature of methoxy‐substituted phenazine derivatives show superior corrosion inhibition properties as 98.96 in 900 ppm than electron withdrawing bromo substituted phenazine derivative in the same concentration which indicates that the electronic structure of the organic inhibitor plays an important role in the corrosion inhibition efficiency of mild steel in an acid medium.ConclusionThe synthesized compound efficiently inhibits the corrosion on the mild steel surface and it forms a barrier on the metal surface. As a result, the phenazine derivatives of both MBPP and BBPP act as very effective corrosion inhibitors and the electron‐donating nature of MBPP shows more inhibition efficiency than BBPP inhibitors.
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