Saida AB,
Chardon A,
Osi A,
Tumanov N,
Wouters J,
Adjieufack AI,
Champagne B,
Berionni G.
* University of Namur, Belgium
Pushing the Lewis Acidity Boundaries of Boron Compounds with Non-Planar Triarylboranes
Derived from Triptycenes.
Angew. Chem. Int. Ed. 2019;
58: 16889-16893
Key words
Lewis acids - triptycenes - protodeboronation
Significance
Trivalent organoboron compounds are an interesting class of materials with applications
in Lewis acid catalyzed reactions. Here, Berionni and co-workers find that embedding
boron in the carbon scaffold of triptycene greatly contributed to the increased Lewis
acidity of the molecule. The boratriptycenes were found to bind various weak Lewis
bases covalently.
Comment
While the synthesis of the 9-boratriptycene was unsuccessful, replacing the C–H bridgehead
with a phosphonium linker proved to be effective. The phosphonium moiety was also
useful as a strong Brønsted acid. This is the first report to describe the coordination
of the non-nucleophilic triflimide anion to a trivalent boron, emphasizing the unrivaled
Lewis acidity of this molecule.
