Electrochemical Bromination of Substituted Thiophenes in Batch and Continuous Flow

An electrochemical bromination of thiophenes from ammonium bromide is developed both in batch and continuous‐flow conditions. Substituted thiophenes possessing 2‐hydrogens selectively afford a series of 2‐bromothiophenes while 2‐substituted benzothiophenes generate 3‐bromobenzo[b]thiophenes. Based on the cyclic voltammetric studies and literature, a bromine cation involved mechanism was proposed. An electrochemical bromination of substituted thiophenes and benzothiophenes from ammonium bromide was developed to produce 2‐bromo thiophenes and 3‐bromobenzo[b]thiophenes with moderate to excellent yields under both batch and continuous flow conditions.