1215840-39-3Relevant academic research and scientific papers
Mechanism of NHC-Catalyzed Conjugate Additions of Diboron and Borosilane Reagents to α,β-Unsaturated Carbonyl Compounds
Wu, Hao,Garcia, Jeannette M.,Haeffner, Fredrik,Radomkit, Suttipol,Zhugralin, Adil R.,Hoveyda, Amir H.
, p. 10585 - 10602 (2015/09/28)
Broadly applicable enantioselective C-B and C-Si bond-forming processes catalyzed by an N-heterocyclic carbene (NHC) were recently introduced; these boryl and silyl conjugate addition reactions (BCA and SCA, respectively), which proceed without the need f
Metal-free catalytic C-Si bond formation in an aqueous medium. enantioselective NHC-catalyzed silyl conjugate additions to cyclic and acyclic α,β-unsaturated carbonyls
O'Brien, Jeannette M.,Hoveyda, Amir H.
supporting information; experimental part, p. 7712 - 7715 (2011/07/09)
A metal-free method for enantioselective conjugate addition of a dimethylphenylsilyl group to α,β-unsaturated carbonyls is reported. Transformations are catalyzed by a chiral N-heterocyclic carbene (NHC), performed in an aqueous solution (3:1 mixture of water and tetrahydrofuran) and are operationally simpler to perform than the NHC-Cu-catalyzed variant. The chiral catalyst is generated from an enantiomerically pure imidazolinium salt (prepared in three steps) and a common organic amine base (dbu). NHC-catalyzed processes proceed with 5.0-12.5 mol % catalyst loading at 22 °C within 1-12 h, affording the desired β-silyl carbonyls in 85:15 to >98:2 enantiomeric ratio and in 50% to >98% yield. Cyclic enones or lactones and acyclic α,β-unsaturated ketones, esters, and aldehydes can be used as substrates.
Enantioselective conjugate silyl additions to cyclic and acyclic unsaturated carbonyls catalyzed by Cu complexes of chiral N-heterocyclic carbenes
Lee, Kang-Sang,Hoveyda, Amir H.
supporting information; experimental part, p. 2898 - 2900 (2010/05/01)
(Figure Presented) An efficient Cu-catalyzed protocol for enantioselective addition of a dimethylphenylsilanyl group to a wide range of cyclic and acyclic unsaturated ketones, esters, acrylonitriles, and α,β,γ,σ- dienones is disclosed. Reactions are performed in the presence of 1-2 mol % of commercially available and inexpensive CuCl, a readily accessible monodentate imidazolinium salt, and commercially available (dimethylphenylsilyl) pinacolatoboron. Cu-catalyzed enantioselective conjugate additions proceed to completion within only 2 h to afford the desired silanes in 87-97% yield and 90:10-99:1 enantiomeric ratio (er). Use of a proton source (e.g., MeOH) is not required; accordingly, synthetically versatile α-silyl boron enolates can be obtained. The special utility of the present protocol, in comparison with the related catalytic enantioselective aldol and boronate conjugate additions, is discussed and illustrated through various functionalizations of the enantiomerically enriched Β-silylcarbonyls. Copyright
