Dual Functionalization of the α,β-C–H Bonds in Alanine Ester Derivatives via Enamine–Imine Tautomerism: Construction of 4-Quinolinolate Skeletons through a Fragmentation–Reassembly Pathway

Using a SbCl₃/O₂ 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.