Organocatalytic iminium-assisted asymmetric B(sp²)-to-B(sp³) transformation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41290572.
- Also identified by DOI 10.1038/s41467-025-65393-9 and PMC identifier 12647797.
- Licence recorded as CC BY-NC-ND.
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Abstract
Tetracoordinate boron compounds are widely used as dyes in medicinal research and material sciences. Current methods for accessing such compounds with a stereogenic boron center rely on chiral substrate-induced diastereoselective reactions or metal-catalyzed desymmetrization of pre-formed tetracoordinate boron molecules. Directly constructing a tetracoordinate B(sp<sup>3</sup>) center in a catalytic enantioselective manner remains challenging and underdeveloped, as controlled asymmetric reactions on a flat B(sp<sup>2</sup>) center are virtually unknown. Here, we address this challenge by leveraging the inherent structural features of commonly used boron compounds. In our approach, the amino-thiourea organocatalyst activates the phenol oxygen of the salicylaldehyde as an effective nucleophile for enantioselective addition to the B(sp²) center of a B,N-heterocyclic substrate. Subsequent iminium exchange involving the amine moiety of the B,N-heterocycle furnishes the tetracoordinate B(sp³) products with excellent optical purities. Our study adopted the B(sp²)-to-B(sp³) transformation strategy for the enantioselective synthesis of tetracoordinate boron molecules.