Lewis acid-mediated transformations of 5-acyl- N -fluoroalkyl-1,2,3-triazoles to cyclopentenones, indenones, or oxazoles.

We present a transition metal-free approach to 2- N -substituted indenones, cyclopentenones, and 4-carbonyl oxazoles, based on the reaction of 5-acylated N -fluoroalkyl substituted 1,2,3-triazoles (prepared by a three-component click reaction of copper acetylides, fluoroalkyl azides, and acyl chlorides) with Lewis acids aluminium trichloride or boron trifluoride etherate, proceeding via the generation and cyclization of vinyl cations.