Pyrroles as Terminators in Cationic Cyclizations. The Preparation of 5,6,7,8-Tetrahydroindolizidines and 6,7,8,9-Tetrahydro-5H-pyrroloazepines

Article abstract of DOI:10.1021/jo00381a021

N-(Epoxyalkyl)pyrroles 8-13 are readily prepared either by direct pyrrole N-alkylation with either ω-iodo epoxides or ω-iodo-1,2-alkanediol acetonides followed by conversion to the corresponding epoxides.The cyclizations of these N-(epoxyalkyl)pyrroles were examined with a range of Lewis acids providing cyclized products 14 and 16-21 in moderate to excellent yields.The cyclization products 14, 16, and 20 are formally the products of "anti-Markovnikov" attack on the less substituted epoxide terminus.