Achievements in photocatalytic Povarov-type reactions: a key step in green diversification of the quinoline chemical space

Abstract

Advances in Povarov reactions under visible-light conditions, leading to the generation of diverse bioactive quinoline molecules, were thoroughly described and analysed. Based on the structural classification of Povarov products, the discussion is organized into three main quinoline groups: (a) simple substituted (tetrahydro)quinolines, (b) tricyclic quinolines, such as pyrrolo[3,4-c]quinolones and furo[3,4-b]quinolinones, and (c) diverse polycyclic quinolines, comprising indolo[3,2-c]quinolines (isocryptolepine alkaloid analogues), and indolizino[1,2-b]quinolin-9-ones (luotonin and camptothecin derivatives). The synthesis of these compounds was examined under metal-based and metal-free visible-light photocatalytic conditions, and comparisons were drawn with analogous conventional Povarov reactions, where applicable. Some mechanistic details of such reactions were also surveyed, offering valuable guidance for selecting appropriate synthetic protocols and predicting strategies for designing target quinoline products under photocatalytic conditions. These insights align with the principles of green synthetic chemistry. The review primarily covers works published between 2010 and 2024, providing a comprehensive overview of recent progress in this field.