Nickel‐Catalyzed Sequential Synthesis of Alkylated Quinolines and Their Photophysical Studies

An efficient nickel‐catalyzed sequential one‐pot strategy for the synthesis of coumarin‐appended quinolines and bis‐quinolines has been developed under mild reaction conditions in moderate to good yields (up to 84 %) via dehydrogenative Friedlander annulation followed by C(sp3)−H functionalization. The use of a cost‐effective Ni catalyst, environmentally friendly solvents and simple operating procedures are the attractive attributes of this method. Additionally, the photophysical properties of the synthesized derivatives were explored utilizing UV‐vis absorption and fluorescence emission studies. Furthermore, the large‐scale synthesis and the synthetic utility of the derivatives highlight the potential applicability of this strategy in synthetic organic chemistry. Moreover, A plausible reaction mechanism is supported by the control experiments and reaction monitoring by 1H NMR analysis. An efficient Ni‐catalyzed one‐pot sequential method has been proposed for the synthesis of coumarin‐containing quinolines and bis‐quinolines. The three‐step sequence, starting with 2‐amino 5‐chloro benzhydrol, yields up to 87 % of coumarin‐containing quinolines and 89 % of bis‐quinolines. This method offers operational simplicity and scalability, facilitating the synthesis of desired products in a short reaction time (8–10 h).