However, none of these factors led to any desired increase in the yield of 3a and 5a, and in most cases, no product formation was achieved (see Supplementary Information section 3.5.3). Substrate scope studies. The substrate scope for the reaction is shown in Fig. . All substrates underwent facile free-radical electrophilic or nucleophilic reactions and furnished the corresponding products in good to excellent yield, irrespective of the presence of electron-donating or electron-withdrawing substituents on the aromatic ring. However, the electron-deficient aromatic rings were conducive to the formation of 2,3-disubstituted quinolines, whereas 3,4-disubstituted quinolines were more readily formed in the presence of electron-donating groups on the aromatic ring (3c, 3g, 5b, and 5d) which is consistent with the electrophilic and nucleophilic free-radical reaction mechanisms, respectively. Moreover, the synthesis of 2,3-disubstituted-quinolines were tolerated by a wide range of functional groups, including the alkoxy and aryl halide groups. In fact, the comparatively unstable hydroxyl products, such as 3b and 3k, also remained intact during the course of the reaction, indicating the relatively mild conditions used for this method. Interestingly, the reaction conditions were also suitable for heteroarenes (3u, 65% yield; 5k, 54% yield). Likewise, 3,4-disubstituted quinolines with phenyl, halo, or methoxy substituents were also obtained in good to excellent yield. We examined the generality of the reaction conditions by replacing the ester group with amides and noted that the yield of the former derivative was mostly higher than that of the latter. Notably, both 2,3-disubstituted and 3,4-disubstituted quinolines, such as 3d, 5d, 5f, and 5g, were synthesised in the presence of methoxy groups on the peripheral aromatic ring. The structure of poly-substituted quinoline derivatives, such as 3s and 5d, were explicitly determined using single-crystal X-ray analysis (see Supplementary Information Figs. ) to confirm the formation of the quinoline ring and further demonstrate the effectiveness of this method for the synthesis of poly-substituted quinolines with a wide array of accompanying structural features and functional groups. Mechanistic studies. We theorised that the imine C-H bond generates carbon radicals via photoinduction and strong base catalysis, which attack the α and β positions of the acrylate (2) to form products 3a and 5a via five possible pathways (Fig. ).