One-Pot, Regioselective Consecutive Multihalogenation of 2,2′-Bithiophene

The one‐pot regioselective consecutive multihalogenation of 2,2′‐bithiophene (1) was demonstrated. Compound 1 was consecutively halogenated with lithium halides such as lithium bromide, chloride, and/or iodide in the presence of lead tetraacetate in chloroform at room temperature or under reflux conditions to give 5‐bromo(or chloro)‐5′‐iodo(or chloro)‐, 3‐bromo(or chloro)‐5,5′‐dibromo(or dichloro, diiodo)‐, 3,3′‐dibromo‐(or dichloro)‐5,5′‐diiodo(or dibromo, dichloro)‐, and 3,3′,5‐tribromo(or trichloro)‐5′‐iodo(or bromo)‐2,2′‐bithiophenes. Notably, this process offers a regioselective method for consecutive multihalogenation in one pot, and the yields and selectivity are also higher than those obtained in the step‐by‐step and concurrent halogenation methods. The regioselective consecutive multihalogenation of 2,2′‐bithiophene as a model compound was demonstrated by using lithium halides and lead tetraacetate in chloroform in one pot. This method offers new possibilities for the control of the regioselectivity and the multiplicity in the halogenation of electron‐rich aromatic compounds.