Radical cyclizations of acylsilanes in the synthesis of (+)-swainsonine and formal synthesis of (−)-epiquinamide

摘要: Abstract Radical cyclization of acylsilane is an useful synthetic methodology. To demonstrate the versatility this method using as a key step, polyhydroxylated indolizidine (+)-swainsonine was synthesized through two different bond connection approaches to construct bicyclic skeleton. In first approach, we used 2,3-isopropylidene- d -ribono-1,4-lactone (20) chiral building block form skeleton 1,6-cyclization. second (S)-(+)-5-oxo-2-tetrahydrofurancarboxylic acid (23) same ring system 1,5-cyclization. Starting from 23, also exo-1-hydroxyquinolizidin-4-one (56), which intermediate in synthesis quinolizidine (−)-epiquinamide.