Tandem Enyne Allene-Radical Cyclization via Sigmatropic Rearrangements

Article abstract of DOI:10.1021/jo00097a002

Enediynes 1, 7, 12, and 16 undergo a tandem <3,3> sigmatropic shift-enyne allene cyclization.Enediynes 7 and 16 are especially interesting because after undergoing a <3,3> sigmatropic shift and enyne allene cyclization, the resultant biradical undergoes a 5-exo radical cyclization.These reactions can be effected by either heating at 150 deg C or by treatment with silver salts followed by heating at 75 deg c.