Chiral Synthesis via Organoboranes. 34. Selective Reductions. 47. Asymmetric Reduction of Hindered α,β-Acetylenic Ketones with B-Chlorodiisopinocampheylborane to Propargylic Alcohols of Very High Enantiomeric Excess. Improved Workup Procedure for the Isol

Article abstract of DOI:10.1021/jo00034a034

The Midland reagent, Alpine-Borane (2a), is excellent for the asymmetric reduction of many acetylenic ketones but it fails with hindered derivatives.On the other hand, B-chlorodiisopinocampheylborane (DIP-Chloride, 4) reacts with hindered α,β-acetylenic k