title: Gold-catalyzed, intramolecular, oxygen-transfer reactions of 2-alkynyl-1,5-diketones or 2-alkynyl-5-ketoesters: scope, expansion, and mechanistic investigations on a new [4+2] cycloaddition.
abstract: The gold-catalyzed intramolecular oxygen-transfer reactions of 2-alkynyl-1,5-diketones or 2-alkynyl-5-ketoesters-obtained from tetra-n-butylammonium fluoride mediated Michael addition of activated allenes to electron-deficient olefins-furnished cyclopentenyl ketones under very mild conditions. These reactions proceeded much easier and faster than similar reactions reported in literature, and the corresponding products were obtained in very good yields. Mechanistic investigations on the cycloisomerization were carried out by means of both (18) O isotopic experiments and quantum chemical calculations. The results from both, the designed isotopic experiments and theoretical calculations, satisfactorily supported the novel proposed intramolecular [4+2] cycloaddition of a gold-containing furanium intermediate to a carbonyl group, instead of the previous well-accepted [2+2] pathway.
authors.affiliation: Department of Chemistry, University of Louisville, KY 40292, USA. leping.liu@louisville.edu
authors.forename: Le-Ping
authors.initials: LP
authors.lastname: Liu
authors.forename: Deepika
authors.initials: D
authors.lastname: Malhotra
authors.forename: Zhuang
authors.initials: Z
authors.lastname: Jin
authors.forename: Robert S
authors.initials: RS
authors.lastname: Paton
authors.forename: K N
authors.initials: KN
authors.lastname: Houk
authors.forename: Gerald B
authors.initials: GB
authors.lastname: Hammond
mesh_terms: D002384:Catalysis; D003500:Cyclization; D004952:Esters; D006046:Gold / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010103:Oxygen Isotopes / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D004952:Esters; D007659:Ketones; D010103:Oxygen Isotopes; D006046:Gold; D010100:Oxygen