The Synthesis of Highly Substituted Cyclooctatetraene Scaffolds by Metal-Catalyzed [2+2+2+2] Cycloadditions: Studies on Regioselectivity, Dynamic Properties, and Metal Chelation


  • This research was supported by a grant (CHE-0450638) from the National Science Foundation. J.P.C and A.B.L. thank Amgen for financial support. M.T.G thanks the Deutscher Akademischer Austauschdienst for financial support. We thank Allen Oliver at the University of California, Santa Cruz and Prateek Verma at Stanford University for X-ray crystal structures. We also thank Kristen Brownell for assisting in substrate preparation.


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All-kynes of COTs: A Ni0-catalyzed [2+2+2+2] cycloaddition of 1,6-diynes yields highly functionalized hexa- and octa-substituted cyclooctatetraenes (COTs; see picture) along with the first example of a fully intramolecular [2+2+2+2] cycloaddition product. The regioselectivity of this process is studied and the initial use of COT ligands is shown in the formation of a ZnII complex with a bis(oxazoline) COT.