Room-Temperature Metal-Free Electrophilic 5-endo-Selective Iodocarbocyclization of 1,5-Enynes

A highly efficient NIS-promoted iodocarbocyclization reaction of various functionalized 1,5-enynes is described via a 5-endo diastereoselective process. The cyclizations are conducted in the presence of 1.2 equiv of N-iodosuccinimide in dichloromethane at room temperature. The reaction conditions are compatible with several functional groups and lead to original iodo-functionalized carbocycles in good to excellent yields.