Synthesis of 3,4,5-Trisubstituted Isoxazoles through Gold-Catalyzed Cascade Cyclization−Oxidative Alkynylation and Cyclization-Fluorination of 2-Alkynone O-Methyloximes

摘要

Gold-catalyzed tandem cyclization−oxidative alkynylation and cyclization-fluorination reactions of 2- alkynone O-methyloximes are described. The reactions proceed smoothly at room temperature in the presence of 10 mol % of (PPh3)AuNTf2, 2.5 equivalents of selectfluor, and 2 equivalents of K3PO4. 2-Alkynone Omethyloximes undergo intramolecular oxyauration/cyclization and ensuing oxidative cross-coupling and fluorination process to afford the corresponding 3,4,5-trisubstituted isoxazoles in a cascade manner.