α-Acylamino Radical Cyclizations: Application to the Synthesis of a Tetracyclic Substructure of Gelsemine

Article abstract of DOI:10.1021/jo00263a006

Syntheses of gelsemine substructures 2 and 3 are described.Free-radical precursors 14,18,35 and 38 were prepared, and their behavior upon treatment with tri-n-butyltin hydride and AIBN was examined.The radical derived from 14 afforded reduction product 15, whereas the radicals derived from 18,35, and 38 gave cyclization products 23,37, and 39, respectively.Aspects of these free-radical cyclizations as well as the conversion of 23 and 37 to 2 and 3, respectively, are presented.