Nature of the intermediates in gold(I)-catalyzed cyclizations of 1,5-enynes.
The carbene or carbocationic nature of the intermediates in the gold-catalyzed cycloisomerization of 1,5-enynes can be revealed, depending on the ligands on the gold catalysts. Gold complexes with highly electron-donating ligands promote reactions that proceed via intermediates with carbene-like character, leading to products with a bicyclo[3.1.0]hexene skeleton. The intermediate cyclopropyl endo-gold carbenes formed in this cyclization have been trapped, for the first time, to give biscyclopropane derivatives in a reaction that proceeds in a concerted fashion, according to DFT calculations.
Institute of Chemical Research of Catalonia (ICIQ), Av. Pasos Catalans 16, 43007 Tarragona, Spain.
Verónica
V
López-Carrillo
Núria
N
Huguet
Ángeles
Á
Mosquera
Antonio M
AM
Echavarren