NMR and X-ray study of the diastereoselective [3+2] cycloaddition reaction of chiral acridine with stable 2,4,6-trimethylbenzonitrile <i>N</i> -oxide

, unambiguously establishes the regiochemistry of the cycloaddition and the relative configuration at the newly formed stereogenic centres. The molecular structures reveal a rigid acridine framework linked to a slightly puckered isoxazoline ring, with the ester substituent adopting distinct orientations depending on the regiochemical outcome. In the solid state, the molecules are stabilized by weak C-H...O contacts involving the isoxazoline and ester functionalities, and by weak C-H...π interactions. These crystallographic results provide reliable structural benchmarks for acridine-based isoxazoline derivatives obtained via 1,3-dipolar cycloaddition reactions.