Selective Removal of Aminoquinoline Auxiliary by IBX Oxidation

Abstract

8-Aminoquinoline (AQ) is a widely used bidentate auxiliary in metal-catalyzed directed C–H functionalization reactions. Herein, we report an efficient and chemoselective method to convert various N-quinolyl carboxamides to primary amides with the treatment of a stoichiometric amount of 2-iodoxybenzoic acid oxidant or the combination of a catalytic amount of 2-iodobenzoic acid and Oxone co-oxidant in mixed solvents of H2O and HFIP. Its unique compatibility with the Phth-protected α-amino acid (αAA) substrates enhances the overall synthetic utility of the AQ-directed palladium-catalyzed C–H functionalization strategy for synthesis of complex αAAs.