title: Synthesis of Bridged Heterocycles via Sequential 1,4- and 1,2-Addition Reactions to α,β-Unsaturated N-Acyliminium Ions: Mechanistic and Computational Studies.
abstract: Novel tricyclic bridged heterocyclic systems can be readily prepared from sequential 1,4- and 1,2-addition reactions of allyl and 3-substituted allylsilanes to indolizidine and quinolizidine α,β-unsaturated N-acyliminium ions. These reactions involve a novel N-assisted, transannular 1,5-hydride shift. Such a mechanism was supported by examining the reaction of a dideuterated indolizidine, α,β-unsaturated N-acyliminium ion precursor, which provided specifically dideuterated tricyclic bridged heterocyclic products, and from computational studies. In contrast, the corresponding pyrrolo[1,2-a]azepine system did not provide the corresponding tricyclic bridged heterocyclic product and gave only a bis-allyl adduct, while more substituted versions gave novel furo[3,2-d]pyrrolo[1,2-a]azepine products. Such heterocyclic systems would be expected to be useful scaffolds for the preparation of libraries of novel compounds for new drug discovery programs.
authors.affiliation: School of Chemistry, University of Wollongong , Wollongong, New South Wales 2522, Australia.
authors.forename: Arife
authors.initials: A
authors.lastname: Yazici
authors.affiliation: School of Chemistry, BIO21 Molecular Science and Biotechnology Institute, University of Melbourne , Melbourne, Victoria 3010, Australia.
authors.forename: Uta
authors.initials: U
authors.lastname: Wille
authors.affiliation: School of Chemistry, University of Wollongong , Wollongong, New South Wales 2522, Australia.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Pyne