C-2 Symmetric and meso-iodo hydroxy ammonium chlorides generated from 2 and 5 have been cyclized under basic conditions to produce various heterocycles chemoselectively, which comprise tetrahydrofurans 7 and 19, piperidines 13, 15 and 21, and pyrrolidines 17 and 18. (C) 1997, Elsevier Science Ltd. All rights reserved.