Mn(II)-Catalyzed Markovnikov Hydroiodination of Terminal Aryl Alkynes

A Mn(II)-catalyzed Markovnikov hydroiodination of terminal aryl alkynes with TMSI as the iodination reagent has been developed. Cheap Mn(OAc)2·4H2O was employed as the catalyst. Twenty-five aryl alkynes (including two internal alkynes) were successfully transformed into their α-iodide styrene derivatives, including those natural product-based alkynes and poly alkynyl benzenes. The reaction has good chemoselectivity of alkynes over alkenes, which enabled the tolerance of olefin in the substrate. Gram-scale synthesis was also conducted.