title: Oxidant-dependent chemoselectivity in the gold-catalyzed oxidative cyclizations of 3,4,6,6-tetrasubstituted 3,5-dien-1-ynes.
abstract: A distinct chemoselectivity in the gold-catalyzed oxidative cyclization of 3,5-dien-1-ynes was observed when 3,5-dichloropyridine N-oxide replaced 8-methylquinoline N-oxide as the oxidant; the resulting cyclopentadienyl aldehydes were obtained in good yields. The altered chemoselectivity is attributed to a prior enyne cyclization in the presence of 3,5-dichloropyridine N-oxides. The use of N-iminopyridium ylide enables a similar iminocyclization reaction to give cyclopentadienyl imines efficiently. Our experimental data support a prior gold-catalyzed cyclization of 3,5-dien-1-ynes to form gold carbene, followed by the oxidation with N-oxide.
authors.affiliation: Department of Chemistry, National Tsing-Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Hsiao-Hua
authors.initials: HH
authors.lastname: Hung
authors.forename: Yi-Ching
authors.initials: YC
authors.lastname: Liao
authors.forename: Rai-Shung
authors.initials: RS
authors.lastname: Liu
mesh_terms: D000447:Aldehydes / Q000138:chemical synthesis* / Q000737:chemistry; D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D015394:Molecular Structure; D050607:Organogold Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D000447:Aldehydes; D000480:Alkynes; D050607:Organogold Compounds