Tf2NH-Catalyzed Formal [3+2] Cycloaddition of Ynamides with Dioxazoles: A Metal-Free Approach to Polysubstituted 4-Aminooxazoles

An unprecedented Tf2NH-catalyzed formal [3 + 2] cycloaddition of ynamides with dioxazoles was developed to construct various polysubstituted 4-aminooxazoles. This approach features a metal-free catalytic bimolecular assembly of oxazole motifs; a low-cost catalyst, exceptionally mild reaction conditions, a very short reaction time, a broad substrate scope, and high efficiency. This metal-free protocol may find applications in pharmaceutical-oriented synthesis.