Synthesis, characterization of new α‐quinolin‐3‐yl‐α‐(aminoamides, aminoesters) and bi‐heterocyclic aromatic systems from gem‐dicyanoepoxides and their pharmacological activity as antioxidant and antifungal agents

Abstract

New series of quinoline coupled to diversely functionalized heterocyclic cores were synthesized, via appropriate synthetic routes, using 3‐(quinolin‐3‐yl) oxirane‐2,2‐carbonitriles as key intermediates. The epoxide ring opening gave bi‐heterocyclic hybrids such as α‐quinolin‐3‐yl‐α‐aminoacetic acid derivatives, quinoxaline‐ and benzimidazole‐quinoline hybrids, and quinoline‐1,3‐oxathioles. Some selected bi‐heterocyclic hybrids were evaluated in vitro for their antioxidant potential using DPPH• and ABTS•+ methods, and their antifungal activity against Fusarium oxysporum f. sp. Lycopersici. It was demonstrated that bi‐heterocyclic aromatic systems exhibited significant antioxidant activities, which are similar in magnitude to those of standards BHT and BHA with important IC50 values. The SAR study of the antifungal activity revealed that only compounds bearing a 2‐imino‐1,3‐oxathiole nucleus are active showing interesting results. Crystal X‐ray structures for two compounds are also reported.