title: Investigation of oxidopyrylium-alkene [5+2] cycloaddition conjugate addition cascade (C3) sequences.
abstract: Novel oxidopyrylium-alkene [5+2] cycloaddition conjugate addition cascade (C(3)) sequences are described. Various acetoxypyranone-alkenes with pendant nucleophiles undergo [5+2] cycloaddition followed by conjugate addition from the concave face of the intermediate pyranone toward bridged, tetracyclic ethers. In several cases, 3 new rings, 4 new bonds, and 6 new contiguous stereocenters are constructed with excellent diastereoselectivity. Finally, an asynchronous concerted reaction pathway is proposed to explain the high diastereoselectivity of the oxidopyrylium-alkene [5+2] C(3).
authors.affiliation: Department of Chemistry, Illinois State University, Normal, IL 61790-4160, USA. tmitche@ilstu.edu.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Simanis
authors.forename: C Marshall
authors.initials: CM
authors.lastname: Law
authors.forename: Erica L
authors.initials: EL
authors.lastname: Woodall
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Hamaker
authors.forename: John R
authors.initials: JR
authors.lastname: Goodell
authors.forename: T Andrew
authors.initials: TA
authors.lastname: Mitchell