Intramolecular Cyclization of N-Propargylic Amides without Transition-Metal Catalysis for Synthesis of Fluoroalkylated Oxazoles: Using Carboxylic Acid Anhydrides as the Fluoroalkyl Source

Abstract

AbstractSynthesis of 2-fluoroalkylated oxazoles was developed by transition-metal-free intramolecular cyclization of N-propargylic amides, which are prepared from propargylic amines by employing a small excess of commercially available fluorocarboxylic acid anhydrides as fluoroalkyl­ sources, under basic conditions. Oxazoles bearing a trifluoro­methyl, pentafluoroethyl, or heptafluoropropyl group at the C2 position and functional groups on the C4 and/or C5 positions are obtained in moderate to high yields by controlling the reaction conditions.