The Synthesis of Indolizidine and Quinolizidine Ring Systems by Free Radical Cyclization of 4-Aza-6-methoxycarbonyl-5-hexenyl Radicals

Article abstract of DOI:10.1016/S0040-4020(01)81101-7

The formation of bicyclic amines by the intramolecular cyclization of 4-aza-6-methoxycarbonyl-5-hexenyl radicals is described.The direct attachment of a nitrogen atom to the double bond changes the electronic nature of the alkene such that the cyclization is less efficient than the all carbon analogue or the other aza-substituted 5-hexenyl cyclizations.The reaction has been used in a short, convenient synthesis of a variety of indolizidines from methyl nicotinate.In addition, the cyclization was used as the key step in a short synthesis of (+/-)-epilupinine from methyl nicotinate.