Abstract
Facile cycloisomerization of (2-ethynylphenyl)alkynes is proposed to be promoted synergistically by two molecules of BrettPhosAuNTf 2, affording tricyclic indenes in mostly good yields. A gold vinylidene is most likely generated as one of the reaction intermediates on the basis of both mechanistic studies and theoretical calculations. Different from the well-known Rh, Ru, and W counterparts, this novel gold species is highly reactive and undergoes facile intramolecular C(sp 3)-H insertions as well as O-H and N-H insertions. The formation step for the gold vinylidene is predicted theoretically to be complex with a bifurcated reaction pathway. A pyridine N-oxide acts as a weak base to facilitate the formation of an alkynylgold intermediate, and the bulky BrettPhos ligand in the gold catalyst likely plays a role in sterically steering the reaction toward formation of the gold vinylidene.
Original language | English (US) |
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Pages (from-to) | 31-34 |
Number of pages | 4 |
Journal | Journal of the American Chemical Society |
Volume | 134 |
Issue number | 1 |
DOIs | |
State | Published - Jan 11 2012 |
Externally published | Yes |