Crystal structure and Hirshfeld-surface analysis of an etoxazole metabolite designated R13

Abstract

The crystal structure of a metabolite of the insecticide/acaricide etoxazole, designated R13 is presented along with a Hirshfeld surface analysis of inter­molecular inter­actions present in the crystal structure.

The etoxazole metabolite R13, systematic name 4-(4-tert-butyl-2-eth­oxy­phen­yl)-2-(2,6-di­fluoro­phen­yl)oxazole (C₂₁H₂₁F₂NO₂), results from the oxidation of etoxazole, a chitin synthesis inhibitor belonging to the oxazoline class, widely used as an insecticide/acaricide since 1998. The structure of R13 features a central oxazole ring with attached 2,6-di­fluoro­phenyl and 4-t-butyl-2-eth­oxy­phenyl moieties. The overall conformation gives dihedral angles between these rings and the oxazole of 24.91 (5)° (with di­fluoro­phen­yl) and 15.30 (6)° (with t-butyl-eth­oxy­phen­yl), indicating an overall deviation from planarity. Additionally, torsion angles of the eth­oxy and t-butyl groups define the orientation of these substituents relative to their benzene ring. In the crystal packing, no significant hydrogen bonds are present, but a Hirshfeld surface analysis highlights weak inter­molecular contacts leading to π–π-stacked dimers linked by weak C—H⋯N contacts. The packing analysis confirms that most inter­molecular inter­actions involve hydrogen atoms.