Enantioselective Iridium-Catalyzed Allylation of Nitroalkanes: Entry to β-Stereogenic α-Quaternary Primary Amines

The first systematic study of simple nitronate nucleophiles in iridium-catalyzed allylic alkylation is described. Using a tol-BINAP-modified pi-allyliridium C,O-benzoate catalyst, alpha,alpha-disubstituted nitronates substitute racemic branched alkyl-substituted allylic acetates, thus providing entry to beta-stereogenic alpha-quaternary primary amines. DFT calculations reveal early transition states that render the reaction less sensitive to steric effects and distinct trans-effects of diastereomeric chiral-at-iridium pi-allyl complexes that facilitate formation of congested tertiary-quaternary C-C bonds.

Automated summary

The systematic study of simple nitronate nucleophiles in iridium-catalyzed allylic alkylation demonstrates the synthesis of beta-stereogenic alpha-quaternary primary amines. DFT calculations reveal early transition states and distinct trans-effects of diastereomeric chiral-at-iridium pi-allyl complexes in facilitating the formation of congested tertiary-quaternary C-C bonds.