Lithium-B-Iso-2-ethylapopinocampheyl-9-borabicyclononyl Hydride as an Improved Reagent for Asymmetric Reduction of Unhindered Aliphatic Ketones. Further Evidence for the Improved Enantioselectivity in Reductions by Reagents Containing Increased Steric Requirements at the ...

Article abstract of DOI:10.1016/S0957-4166(00)86346-6

Lithium B-iso-2-ethylapopinocampheyl-9-borabicyclo<3.3.1>nonyl hydride (Eapine-Hydride), prepared by hydroboration of 2-ethylapopinene with 9-borabicyclo<3.3.1>nonane, followed by treatment with tert-butyllithium, is as effective as NB-Enantride for the chiral reduction of prochiral ketones.For example Eapine-Hydride reduces 2-octanone, 3-methyl-2-butanone, and acetylcyclohexane in 77percent (75percent, 79percent), 77percent (68percent), and 80percent (80percent) ee, respectively, at -100 deg C. (Values in parenthesis are for NB-Enantride).