NHC-stabilized gold(I) complexes: Suitable catalysts for 6-exo-dig heterocyclization of 1-(o-Ethynylaryl)ureas

Ana Gimeno, Mercedes Medio-Simón, Carmen Ramírez De Arellano, Gregorio Asensio, Ana B. Cuenca

Research output: Indexed journal article Articlepeer-review

58 Citations (Scopus)


Figure presented 3-substituted 1-(o-ethynylaryl)ureas 1 selectively undergo either 6-exo-dig or 5-endo-dig cyclization (to give 4-methylene-3,4-quinazolin- 2-ones 2 or indoles 3, respectively) depending on the choice of the metal, ligand, and reaction conditions. The best results (up to 96% yield) in the preparation of the hydroamination products 2 are achieved with the highly bulky NHC-stabilized cationic gold(I) complex [Au(IPr)]+. Conversely, ureas bearing an internal alkyne lead to the 5-endo-dig cyclization mode regardless of the gold(I) complex employed. Whereas the nature of the substituent at N-3 does not have any influence on the regiochemistry observed, it does, in some cases, affect the efficiency of these transformations.

Original languageEnglish
Pages (from-to)1900-1903
Number of pages4
JournalOrganic Letters
Issue number9
Publication statusPublished - 7 May 2010
Externally publishedYes


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