HIGH-TEMPERATURE RADICAL CYCLIZATION ANOMALIES IN THE TANDEM ENEDIYNE-BIS-RADICAL CYCLIZATION

Previous reports have shown that the thermolysis of aromatic enediynes containing radical accepting tethers will undergo tandem enediyne-radical cyclizations. Herein will be reported several examples of the tandem enediyne-bis-radical cyclization where non-radical accepting tethers will undergo cyclizations to aromatic rings to result in cyclization products. Most of the unusual products result from 1,5-hydrogen abstraction, followed by either p-elimination or radical addition to the aromatic ring. The synthesis of the aromatic enediynes, mechanisms, as well as, the thermolysis products are described.