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Chiral Molecular Propellers of Triarylborane Ammonia Adducts
Author(s) -
Kemper Michael,
Engelage Elric,
Merten Christian
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202014130
Subject(s) - chirality (physics) , steric effects , chemistry , adduct , intramolecular force , racemization , molecule , borane , hydrogen bond , stereochemistry , computational chemistry , organic chemistry , chiral symmetry breaking , catalysis , physics , quantum mechanics , nambu–jona lasinio model , quark
Chiral molecular propeller conformations have been induced to various triaryl structures including trityl derivatives and triaryl boranes. For borane–amine adducts, such induced propeller chirality has not been reported yet due to the low energy barrier for racemization in common triarylboranes such as B(C 6 H 5 ) 3 or B(C 6 F 5 ) 3 . Herein, we demonstrate that point chirality in side chains of chiral triarylborane–ammonia adducts, which feature intramolecular hydrogen bonds in addition to the dative N→B bond, can efficiently be transferred to triarylborane propeller chirality. Employing X‐ray crystallography and ECD/VCD spectroscopy for structural characterizations, we investigate three examples with different steric demands of the incorporated chiral alkoxy side groups. We elucidate the conformational preferences of the molecular propellers. Furthermore, we show that computationally predicted conformational preferences obtained for the isolated, only implicitly solvated molecules are actually opposite to the experimentally observed ones.