Electrochemical cascade reactions: an account of recent developments for this modern strategic tool in the arsenal of chemical synthesis

Abstract

In view of the growing demand for synthetic molecules or materials by researchers from both the core sciences and interdisciplinary sectors, the field of organic synthesis needs to be strategically more powerful to produce more molecules in a shorter time. Ensuring a reduction in the use of solvents, catalysts, reagents, time, effort, and waste is essential during green chemical syntheses. Keeping those criteria in mind, the integration of chemical reactions is very much needed. Integrated organic synthesis can be considered the ideal replacement for stepwise synthesis to fulfill demand while maintaining green parameters. The electrochemical cascade process satisfies the essential criteria of greener integrated synthesis to a great extent, providing a modern strategic tool in the arsenal of synthetic chemists. The strategy is applied extensively by researchers, as evidenced by the growing number of publications, amounting to more than a hundred papers on the development of synthesis methods using electrochemical cascade reactions. A thorough understanding of the process is needed to implement the strategy further in targeted synthesis and methodology development for cutting-edge research. To grow the concept among researchers, a concise account of published articles on the topic, depicting the mechanisms, prospects, and problems of the developed methods, is highly desirable. Quenching the thirst herein, we present a concise review of electrochemical cascade processes reported in the literature since 2015. The precedent reactions developed earlier are also discussed in this context. Electrochemical multicomponent reactions involving the cascade process are also covered, expanding the scope of the review. The sections are classified based on the types of functionalization. The mechanistic details of each category of reactions are thoroughly covered to present a clear idea of the redox behavior of different reagents under electrochemical conditions. The prospects and problems associated with the methods are also discussed.