Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
J Am Chem Soc. 2010 Mar 10;132(9):2898-900. doi: 10.1021/ja910989n.
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 alpha,beta,gamma,delta-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 alpha-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 beta-silylcarbonyls.
一种高效的铜催化对映选择性加成二甲基苯基硅烷基到广泛的环状和非环状不饱和酮、酯、丙烯腈和α，β，γ，δ-二烯酮的方法被公开。反应在商业可得且廉价的 CuCl（1-2mol%）、易得的单齿咪唑啉翁盐和商业可得的（二甲基苯基硅基）频哪醇硼酸酯的存在下进行。铜催化的对映选择性共轭加成仅在 2 小时内完成，以 87-97%的产率和 90:10-99:1 的对映体比率（er）得到所需的硅烷。不需要质子源（例如 MeOH）的使用；因此，可以获得合成多功能的α-硅基硼烯醇盐。通过对映体富集的β-硅羰基的各种官能化，讨论并说明了本方法与相关的催化对映选择性羟醛和硼酸酯共轭加成相比的特殊用途。
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