title: Computational and experimental investigations of the formal dyotropic rearrangements of Himbert arene/allene cycloadducts.
abstract: The fascinating intramolecular arene/allene cycloaddition discovered by Himbert affords dearomatized, polycyclic intermediates with sufficient strain energy to drive rearrangement processes of the newly formed ring system. We disclose a detailed examination of a thermally induced stepwise dyotropic skeletal rearrangement of these cycloadducts, a reaction also first described by Himbert. We offer computational evidence for a two-stage mechanism for this formal dyotropic rearrangement and provide rationalizations for the significant substitution-dependent rate differences observed in experiments. These investigations led to the development of a Lewis-acid-catalyzed rearrangement of precursors that were unreactive under simple thermal instigation. The isolation of the product of an "interrupted" rearrangement under Lewis acidic conditions provides further support for the proposed stepwise mechanism. Computational results also matched experiments in terms of regiochemical preferences in unsymmetrical rearrangement precursors and explained why lactam O-, S-, and C-heterologues do not easily undergo this rearrangement.
authors.affiliation: †Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States.
authors.forename: Hung V
authors.initials: HV
authors.lastname: Pham
authors.affiliation: ‡1102 Natural Sciences II, Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Karns
authors.affiliation: ‡1102 Natural Sciences II, Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Vanderwal
authors.affiliation: †Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States.
authors.forename: K N
authors.initials: KN
authors.lastname: Houk
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D003500:Cyclization; D015394:Molecular Structure; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D000475:Alkenes; D011083:Polycyclic Compounds