Oxidopyrylium-Alkene [5 + 2] Cycloaddition Conjugate Addition Cascade (C3) Sequences: Scope, Limitation, and Computational Investigations.
Riley H KaufmanChunyin M LawJustin A SimanisErica L WoodallChristian R ZwickHenry B WedlerPaul WendelboeChristopher G HamakerJohn R GoodellDean Joseph TantilloT Andrew MitchellPublished in: The Journal of organic chemistry (2018)
Oxidopyrylium-alkene [5 + 2] cycloaddition conjugate addition cascade (C3) sequences are described. Intramolecular cycloadditions involving terminal alkenes, enals, and enones were investigated. Substrates with tethers of varying lengths delivered five- and six-membered carbocycles and heterocycles thus demonstrating the scope and limitation of the cycloaddition-conjugate addition cascade. Several experiments and theoretical calculations provide evidence for the proposed mechanistic pathway.