Pyrroles as terminators in cationic cyclizations. The preparation of 5,6,7,8-tetrahydroindolizidines and 6,7,8,9-tetrahydro-5H-pyrrolo[1,2-a]azepines

• Published in: Journal of organic chemistry Vol. 52; no. 5; pp. 819 - 827
• Main Authors: Tanis, Steven P, Raggon, Jeffrey W
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.03.1987; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Organic; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Organic chemistry; Physical Sciences; Preparations and properties; Science & Technology; Five membered ring; Cyclization; Angular nitrogen heterocycle; Nitrogen heterocycle; Bicyclic compound; Mass spectrum; Infrared spectrum; Oxygen heterocycle; NMR spectrum
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo00381a021

N-(Epoxyalkyl)pyrroles 8-13 are readily prepared either by direct pyrrole N-alkylation with either .omega.-iodo epoxides or .omega.-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.