We report a highly regioselective metal-free oxidative cyclization of sulfonamides onto tethered, unactivated alkenes using hypervalent iodine and Bronsted acids. Under these conditions the acid counterion is incorporated into the cyclized products providing an overall aminotrifluoroacetoxylation of the alkene. An unusual preference for endo ring closure is exhibited in contrast to existing exo selective methods. Multiple ring sizes can be formed to access functionalized pyrrolidines, piperidines, and azepanes with a general preference for endo cyclization. A variety of substrate Substitution patterns were tolerated to provide nitrogen-containing heterocycles with high regioselectivities and good to excellent diastereoselectivities.