title: Gold-catalyzed assembly of heterobicyclic systems.
abstract: We have described an efficient gold-catalyzed double cyclization of 1,5-enynes to afford a range of heterobicyclic compounds, including oxabicylclo[3.2.1]octenes, azabicyclo[3.2.1]octenes, oxaspiro[5.4]decene, azaspiro[5.4]decene, oxaspiro[5.5]undecene, oxabicyclo[4.3.0]nonene, azabicyclo[4.3.0]nonene, and oxabicyclo[4.4.0]decene. The mechanism of this reaction is proposed to involve a chemoselective gold-based alkyne activation, carbocyclization, intramolecular nucleophilic addition, followed by protodemetalation. The most notable aspect of this process is the efficient and diastereospecific interception of the reactive intermediate of the initial 6-endo-dig (or 5-endo-dig) cyclization with either oxygen- or nitrogen-based nucleophiles.
authors.affiliation: Department of Chemistry, University of Chicago, 5735 South Ellis Avenue, Chicago, IL 60637, USA.
authors.forename: Liming
authors.initials: L
authors.lastname: Zhang
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Kozmin