Larouche-Gauthier R, Elford TG, Aggarwal VK * University of Bristol, UK
Ate Complexes of Secondary Boronic Esters as Chiral Organometallic-Type Nucleophiles for Asymmetric
Synthesis.
J. Am. Chem. Soc. 2011;
133: 16794-16797
Key words
ate complexes - boronic esters - asymmetric synthesis
Significance
The authors report that secondary chiral boronic esters can be converted into reactive nucleophiles by addition of an aryllithium reagent. These enantiomerically enriched nucleophiles react with a broad range of electrophiles with inversion
of stereochemistry.
Comment
By changing the substituents on the aryl group on boron, a switch in mechanism from a classical 2e– pathway (nucleophilic substitution) to a radical pathway was observed. Therefore, electron-poor boronic esters favor the desired
nucleophilic substitution, whereas electron-rich esters give racemized products.
