Convenient Chlorination with Concentrated Hydrochloric Acid in the Presence of Iodosylbenzene

An efficient chlorination of β-keto esters, 1,3-diketones, and alkenes was performed conveniently with concentrated HCl in the presence of PhIO, selectively giving α-chloro-β-keto esters, 2-chloro-1,3-diketones, and 1,2-dichloroalkanes, respectively. It was suggested that the chlorination took place with (dichloroiodo)benzene generated in situ. A selective anti-addition was observed in the chlorination of indene.