Tuning the strain effect to induce selectivity through intramolecular nitrene insertion into an adjacent methoxy CH bond leading to form a new benzoxazole: experimental and computational studies

•The lactone fused aryl azide reacts intramolecularly with adjacent o-methoxy group.•Loss of nitrogen from the azide is accompanied by two hydrogen atoms, which is rare.•Ring strain induced using the lactone ring in aryl nitrene leads to sole product.•DFT results showed the formation of oxazolidine intermediate than azirine, ketenimine.