Beneficial Effects of Electrochemistry in Cross-Coupling Reactions: Electroreductive Synthesis of 4-Aryl- or 4-Heteroaryl-6-pyrrolylpyrimidines

The rarely described 4‐(hetero)aryl‐6‐pyrrolylpyrimidines are prepared by electroreductive nickel‐catalysed cross‐coupling reactions between aryl halides and chloropyrimidines. Inherent predictable issues of such metal‐catalysed reactions that involve or produce highly nitrogenated compounds – like catalyst poisoning – are tackled by the process described in this paper. The relevance of the strategy is validated by a thorough comparison of the results obtained under electrochemical conditions with those obtained under classical Suzuki–Miyaura conditions. Nickel‐catalysed electroreductive cross‐coupling of 4‐chloro‐6‐pyrrolylpyrimidines and aryl or heteroaryl halides is described as a reliable method for the synthesis of 4‐aryl‐ or 4‐heteroaryl‐6‐pyrrolylpyrimidines. About 20 new compounds were prepared in moderate to good yields. The results of the electrochemical coupling are compared to those obtained under classical Suzuki–Miyaura conditions.