Tf2O-induced selective 1,3-transposition/cyclization of ynones in DMF†

A chemo- and regioselective system for activating CO and SO bonds under transition metal-free conditions is described. Thus, a Tf₂O-mediated 1,3-transposition of ynones in DMF has been developed, providing a versatile pathway for the downstream synthesis of diverse five- and seven-membered heterocycles. Furthermore, the catalytic migration of the carbonyl functionality conjugated to an alkyne unit is investigated. In the presence of sulfoxide, which undergoes a Pummerer reaction, the in situ generation of highly reactive sulfonium salts enables efficient access to a wide range of sulfur-containing annulated scaffolds. Importantly, 3-SCF₂D-substituted chromones were obtained in high yields with high D-incorporation. This divergent methodology offers a versatile platform for maximizing molecular complexity and diversity.