Electrochemical Synthesis of Tetrahydroquinolines from Imines and Cyclic Ethers via Oxidation/Aza‐Diels‐Alder Cycloaddition

Abstract Electrochemical synthesis of cyclic ether‐annulated tetrahydroquinolines from imines and cyclic ethers in an undivided cell under constant current conditions was developed. The electrosynthesis proceeds via the enol ether formation from ethers following the aza‐Diels‐Alder [4+2] cycloaddition. The method is applicable to a wide range of imines and results in the desired products in yields of 23 to 75%. In situ preparation of imines from the corresponding anilines and aldehydes led to mostly the same yields of tetrahydroquinolines. No cycloaddition products were formed using the chemical oxidants. Synthesized cyclic ether‐annulated tetrahydroquinolines exhibit high antifungal activity, which is superior to the commercial fungicide Triadimefon. magnified image