Non-planar Boron Lewis Acids Taking the Next Step: Development of Tunable Lewis Acids, Lewis Superacids and Bifunctional Catalysts
Aurélien Chardon
,
Arnaud Osi
,
Damien Mahaut
,
Ali Ben Saida
,
Guillaume Berionni∗
Department of Chemistry, Namur Institute of Structured Matter, University of Namur, 61, rue de Bruxelles, 5000 Namur, Belgium Email: guillaume.berionni@unamur.be
› Author AffiliationsWe thank the University of Namur, the Namur Institute of Structured Matter (NISM), the Fond National de la Recherche Scientifique (MIS impulsion grant; FNRS grant F.4513.18 for G.B.) and the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA PhD grants for A.O. and D.M.) for financial support.
This paper is dedicated to Prof. Paul Knochel with respect and admiration
Abstract
Although boron Lewis acids commonly adopt a trigonal planar geometry, a number of compounds in which the trivalent boron atom is located in a pyramidal environment have been described. This review will highlight the recent developments of the chemistry and applications of non-planar boron Lewis acids, including a series of non-planar triarylboranes derived from the triptycene core. A thorough analysis of the properties and of the influence of the pyramidalization of boron Lewis acids on their stereoelectronic properties and reactivities is presented based on recent theoretical and experimental studies.
1 Non-planar Trialkylboranes
2 Non-planar Alkyl and Aryl-Boronates
3 Non-planar Triarylboranes and Alkenylboranes
3.1 Previous Investigations on Bora Barrelenes and Triptycenes
3.2 Recent Work on Boratriptycenes from Our Research Group
4 Applications of Non-planar Boranes
4.1 Non-planar Alkyl Boranes and Boronates
4.2 Non-planar Triarylboranes (Boratriptycenes)
5 Other Non-planar Group 13 Lewis Acids
6 Further Work and Perspectives
Key words
boron Lewis acids -
structural constraint -
Lewis superacids -
triarylboranes -
boratriptycenes
References
1a
Hall DG.
Boronic Acids: Preparation and Applications in Organic Synthesis, Medicine and Materials. Wiley-VCH; Weinheim: 2011
8b During the editing process of this manuscript, similar structures have been studied by the group of Alkorta et al. and were predicted to form stable complexes with the dihydrogen molecule. Comparison with other non-planar structures showed that the pyramidalization of the boron atom was a key parameter for the formation of these complexes, see ref:
Alkorta I,
Elguero J,
Oliva-Enrich JM.
Struct Chem 2020;
33b For another recent quantum chemical study of boroadamantane derivatives with dihydrogen, see:
Olivia-Enrich J.-M,
Alkorta I,
Elguero J.
Molecules 2020; 25: 1042