Lewis Acid-Induced π-Cyclization of Glycine-Cation Equivalents to Substituted Pipecolic Acid Derivatives
26 February 2002 (online)
Intramolecular reactions of glycine-cation equivalents with simple olefins, induced by SnCl4, lead to pipecolic acid derivatives. A bicyclic dioxonium ion is proposed as the crucial intermediate in these reactions, which mainly lead to either cis-4-hydroxy- or trans-4-chloropipecolic esters, dependent on the work-up conditions. A bicyclie (indolizidine) and tricyclic skeleton are also readily accessible.