High Asymmetric Induction in the Chiral Hydroboration of Trans Alkenes with Isopinocampheylborane. Evidence for a Strong Steric Dependence in Such Asymmetric Hydroborations

Article abstract of DOI:10.1021/jo00337a060

Isopinocampheylborane, IpcBH2 (2), achieves asymmetric hydroboration of trans-disubstituted alkenes with exceptionally high asymmetric induction.The product alcohols, obtained after oxidation of the intermediate organoboranes, exhibit enantiomeric purities in the range 70-92percent ee.The enantiomeric purities of the products increase with the increasing steric requirement of the alkyl substituent in the trans-disubstituted alkene.