Selective Removal of Aminoquinoline Auxiliary by IBX Oxidation

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.