Abstract
Molecules containing an atropisomeric C–N biaryl axis are gaining increasing attention in catalytic and medicinal chemistry. Despite this rising interest, relatively few approaches towards their catalytic enantioselective synthesis have been reported. Here we review these approaches, with a focus on the mechanism of asymmetric induction. Some common themes emerge: Brønsted acid catalysed cyclo-condensation and palladium-catalysed ring-closure are the most common and successful approaches. Meanwhile, the more direct but challenging axial C–N bond formation strategy remains in its infancy, with just two reports to-date. We hope this review will inform and inspire other researchers to develop new creative approaches to this important chemical motif.
1 Introduction
2 Cyclo-Condensation
3 Proximal C–N Bond Formation
4 Desymmetrisation of Intact Axes
5 ortho-C–H Functionalisation
6 Cycloaddition
7 Axial C–N Bond Formation
8 Atropisomeric N–N Axes: An Emerging Class of Heterobiaryls
9 Conclusion and Outlook
Key words
enantioselectivity - atropisomerism - asymmetric catalysis - axial chirality - heterocycles - heterobiaryls
