Chiral Spirobipyridine Synthesis by Cobalt-Catalyzed Enantioselective Double [2+2+2] Cycloaddition

Abstract

Chiral spirobiindanes are recognized as the privileged structures in the field of asymmetric catalysis. However, the structurally similar chiral spirobipyridines have not yet been explored as chiral ligands or organocatalysts due to the absence of efficient synthetic methods. Herein, we report a cobalt-catalyzed regiodivergent and enantioselective synthesis of spirobipyridines via double [2+2+2] cycloaddition reaction. Spirobipyridines with ortho- or meta-substituents could be obtained with exclusive regioselectivity and up to 99% ee in the presence of cobalt and bisoxazolinephosphine ligands. Spirobipyridines coordinate with transition metals as chiral ligands. Spirobipyridine dioxides can be applied as chiral organocatalysts in the asymmetric allylation of aldehydes.