Using a SbCl 3 /O 2 mild oxidation system, a dual functionalization of the α,β-C−H bonds in alanine ester derivatives was achieved via enamine−imine tautomerism, and a series of quinoline-4-carboxylates were synthesized through a fragmentation− reassembly pathway. The investigation of the substrate scope revealed that various functional groups were easily tolerated, highlighting that this reaction provided an efficient path for the construction of the quinoline-4-carboxylate framework.Letter pubs.acs.org/OrgLett