Electrochemical [3+2] Cycloaddition Proceeding at Low Electrolyte Concentration in Laminar‐Flow Microreactor

Abstract The electrochemical [3+2] cycloaddition of phenols and alkenes in a laminar‐flow microreactor was realized at an unprecedentedly low electrolyte concentration (0.001–0.01 M) owing to low solution resistance derived from the narrow electrode distance. An overoxidation of the resulting cycloadducts (dihydrobenzofuran derivatives) was avoided through the optimization of the reactor configuration, and nine of dihydrobenzofuran derivatives are successfully synthesized in our system without any oxidant. Furthermore, simple scale‐up was enabled by using parallel stacked flow cell system.