Participation of Organotin Lewis Acids in Radical Reactions;- Manipulation of Rotamer Population in N-Enoyloxazolidinones

摘要

Strategies involving radical intermediates have emerged as important tools in synthetic organic chemistry. Since most radical reactions proceed through early transition states, the geometries of the reactants play an important role in the regio-and stereochemical outcomes. The rotamer populations of components in radical reactions have been controlled by factors such as temperature, Lewis acids, dipole—dipole interactions, and steric interactions. In this communication we demonstrate that temperature and/or Lewis acids can control the rotamer populations of N-enoyloxazolidinones (A—D), leading to selective intramolecular radical cyclizations. The results show for the first time that organotin halides, ubiquitous byproducts of many radical reactions, can function as Lewis acids and alter the course of these reactions.