Tf ₂ O-mediated multistate reactivity to access <i>N</i> -acyl and <i>N</i> -aryl azacycles: late-stage modification of bioactive scaffolds

<i>N</i>-Acyl and <i>N</i>-aryl azacycles are widely recognized pharmacophores, recurring in heterocyclic frameworks that drive biological activity and drug-like properties. Herein, we report an operationally simple, efficient, Tf₂O-driven activation of THF and cyclic amines to afford reactive triflate intermediates that assemble with nitriles or arylamines, followed by cyclization-elimination to furnish <i>N</i>-acyl and <i>N</i>-aryl azacycles. This methodology enables the construction of both five- and six-membered heterocyclic frameworks and accommodates deconstructive fluorination to afford mono-fluorinated derivatives, enamides, and late-stage functionalization of bioactive scaffolds.