Ligand-controlled product selectivity in gold-catalyzed double cycloisomerization of 1,11-dien-3,9-diyne benzoates

Weidong Rao; Dewi Susanti; Benjamin James Ayers; Philip Wai Hong Chan

doi:10.1021/jacs.5b02377

Ligand-controlled product selectivity in gold-catalyzed double cycloisomerization of 1,11-dien-3,9-diyne benzoates

J Am Chem Soc. 2015 May 20;137(19):6350-5. doi: 10.1021/jacs.5b02377. Epub 2015 May 7.

Authors

Weidong Rao¹, Dewi Susanti¹, Benjamin James Ayers¹, Philip Wai Hong Chan^{2

3

1}

Affiliations

¹ §Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
² †School of Chemistry, Monash University, Clayton, Victoria 3800, Australia.
³ ‡Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom.

PMID: 25905645
DOI: 10.1021/jacs.5b02377

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.