Under metal- and ligand-free conditions, the economical and accessible CF₃SO₃H successfully catalyzed homogeneous O–H bond insertion reactions between hydroxyl compounds and diazo compounds. Including phenols, alcohols, water and oximes, these O–H bond insertion reactions are very general and functional-group tolerant. Here, we first report the O–H bond insertion of oximes (ketoximes and aldoximes), and their structures were characterized by X-ray crystallography. Moreover, a simple and effective method for S–H insertion reactions of thiols was also developed, delivering the desired C–S bond products with good to excellent yields. It is worth noting that the efficacy of the developed methodology could be further shown by the expeditious synthesis of the PPAR agonist MBX-102 acid.