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Pushing the Lewis Acidity Boundaries of Boron Compounds With Non‐Planar Triarylboranes Derived from Triptycenes
Author(s) -
Ben Saida Ali,
Chardon Aurélien,
Osi Arnaud,
Tumanov Nikolay,
Wouters Johan,
Adjieufack Abel I.,
Champagne Benoît,
Berionni Guillaume
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201910908
Subject(s) - lewis acids and bases , chemistry , adduct , phosphonium , boron , covalent bond , bifunctional , reactivity (psychology) , aryl , cationic polymerization , frustrated lewis pair , crystallography , inorganic chemistry , alkyl , polymer chemistry , organic chemistry , catalysis , medicine , alternative medicine , pathology
Bending the planar trigonal boron center of triphenylborane by connecting its aryl rings with carbon or phosphorus linkers gave access to a series of 9‐boratriptycene derivatives with unprecedented structures and reactivities. NMR spectroscopy and X‐ray diffraction of the Lewis adducts of these non‐planar boron Lewis acids with weak Lewis base revealed particularly strong covalent bond formation. The first Lewis adduct of a trivalent boron compounds with the Tf 2 N − anion illustrates the unrivaled Lewis acidity of these species. Increasing the pyramidalization of the boron center and using a cationic phosphonium linker resulted in an exceptional enhancement of Lewis acidity. Introduction of a phosphorus and a boron atom at each edge of a triptycene framework, allowed access to new bifunctional Lewis acid‐base 9‐phospha‐10‐boratriptycenes featuring promising reactivity for the activation of carbon‐halogen bonds.