NIS-Mediated Electrophilic Cyclization of 3‑Silyloxy-1,n‑enynes

The electrophilic cyclization of 3-silyloxy-1,5-enynes and 3-silyloxy-1,6-enynes was investigated. In the presence of N-iodosuccinimide (NIS), the title compounds are transformed under metal-free conditions into five-membered carbocycles with all-carbon stereogenic centers following a sequence of iodonium activation of the triple bond, carbocyclization, and pinacol-type 1,2-shift.