title: Chemoselectivity control: gold(I)-catalyzed synthesis of 6,7-dihydrobenzofuran-4(5H)-ones and benzofurans from 1-(alkynyl)-7-oxabicyclo[4.1.0]heptan-2-ones.
abstract: New and chemoselective gold(I)-catalyzed transformations of 1-(arylethynyl)-7-oxabicyclo[4.1.0]- heptan-2-ones were developed. Two completely different products--6,7-dihydrobenzofuran-4(5H)-ones and benzofurans--could be obtained from the same starting material. The selectivity is determined by the ligand of the gold catalyst: triphenylphosphine delivers 6,7-dihydrobenzofuran-4(5H)-ones, and 1,3-bis(diisopropylphenyl)imidazol-2-ylidene leads to benzofurans. Eleven examples of each case are provided. The mechanistic suggestions for the pathways to both product types are supported by isotope labeling experiments.
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany), Fax: (+49) 6221-54-4205.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Shuai
authors.initials: S
authors.lastname: Shi
authors.forename: Mie Højer
authors.initials: MH
authors.lastname: Vilhelmsen
authors.forename: Tuo
authors.initials: T
authors.lastname: Zhang
authors.forename: Matthias
authors.initials: M
authors.lastname: Rudolph
authors.forename: Frank
authors.initials: F
authors.lastname: Rominger
authors.forename: A Stephen K
authors.initials: AS
authors.lastname: Hashmi
keywords: annulation; chemoselectivity; gold; ligand effects; synthetic methods