Green Synthesis of Potential Antifungal Agents: 2‑Benzyl Substituted Thiobenzoazoles

Abstract

A series of benzyl-substituted thiobenzoazoles were synthesized by an environmentally friendly approach, to search for new antifungal agrochemicals. Compounds were prepared starting from 2-mercaptobenzoazoles, using KOH, benzyl halides, and water, resulting in a simple and ecological method. New antifungals were tested against a group of phytopathogenic fungi. Two compounds showed an interesting activity against <i>Botrytis cinerea</i>, <i>Fusarium oxysporum</i>, and <i>Aspergillus</i> spp.: 2-((4-(trifluoromethyl)­benzyl)­thio)­benzo­[<i>d</i>]­thiazole, <b>3ac</b>, and 2-((4-methylbenzyl)­thio)­benzo­[<i>d</i>]­thiazole, <b>3al</b>. Thus, <b>3ac</b> and <b>3al</b> can be considered as broad spectrum antifungal agents. Furthermore, two new compounds, 2-((4-iodobenzyl)­thio)­benzo­[<i>d</i>]­thiazole, <b>3aj</b>, and 2-(benzylthio)­benzo­[<i>d</i>]­oxazole, <b>3ba</b>, showed better inhibitory effect against <i>Botrytis cinerea</i> and <i>Fusarium oxysporum</i> when compared to the commercial fungicide Captan. Thus, <b>3aj</b> and <b>3ba</b> can be considered reduced-spectrum antifungals