1239568-91-2Relevant academic research and scientific papers
Enantioselective synthesis of boron-substituted quaternary carbons by NHC-Cu-catalyzed boronate conjugate additions to unsaturated carboxylic esters, ketones, or thioesters
Obrien, Jeannette M.,Lee, Kang-Sang,Hoveyda, Amir H.
supporting information; experimental part, p. 10630 - 10633 (2010/11/05)
A Cu-catalyzed method for enantioselective boronate conjugate additions to trisubstituted alkenes of acyclic α,ss-unsaturated carboxylic esters, ketones, and thioesters is disclosed. All transformations are promoted by 5 mol % of a chiral monodentate NHC-Cu complex, derived from a readily available C1-symmetric imidazolinium salt, and in the presence of commercially available bis(pinacolato)diboron. Reactions are efficient (typically, 60% to >98% yield after purification) and deliver the desired ss-boryl carbonyls in up to >98:2 enantiomer ratio (er). Processes involving unsaturated thioesters proceed with higher enantioselectivity (vs carboxylic esters or ketones), and the resulting products can be functionalized by Ag-mediated or Pd-catalyzed reactions that furnish the derived carboxylic ester or various ketones. Routine oxidation affords ss-hydroxy ketones or carboxylic esters, ketone aldol products that cannot be otherwise prepared efficiently by an alternative catalytic enantioselective protocol.
