title: Ligand-controlled product selectivity in gold-catalyzed double cycloisomerization of 1,11-dien-3,9-diyne benzoates.
abstract: A synthetic method to prepare tricyclic bridged heptenones and hexenones from gold(I)-catalyzed double cycloisomerization of 1,11-dien-3,9-diyne benzoates is described. A divergence in product selectivity was achieved by fine-tuning the steric nature of the ligand of the Au(I) catalyst. In the presence of [MeCNAu(JohnPhos)](+)SbF6(-) (JohnPhos = (1,1'-biphenyl-2-yl)-di-tert-butylphosphine) as the catalyst, tandem 1,3-acyloxy migration/metallo-Nazarov cyclization/1,6-enyne addition/Cope rearrangement of the substrate was found to selectively occur to afford the bridged heptenone adduct. In contrast, changing the Au(I) catalyst to [MeCNAu(Me4tBuXPhos)](+)SbF6(-) (Me4tBuXPhos = di-tert-butyl(2',4',6'-triisopropyl-3,4,5,6-tetramethyl-[1,1'-biphenyl]-2-yl)phosphine) was observed to result in the 1,11-dien-3,9-diyne benzoate undergoing a more rapid tandem 1,3-acyloxy migration/metallo-Nazarov cyclization/[4 + 2]-cyclization pathway to give the bridged hexenone derivative.
authors.affiliation: §Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Weidong
authors.initials: W
authors.lastname: Rao
authors.affiliation: §Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Dewi
authors.initials: D
authors.lastname: Susanti
authors.affiliation: §Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Benjamin James
authors.initials: BJ
authors.lastname: Ayers
authors.affiliation: †School of Chemistry, Monash University, Clayton, Victoria 3800, Australia.|‡Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom.|§Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Philip Wai Hong
authors.initials: PW
authors.lastname: Chan