Rhodium-Catalysed Coupling of Allylic, Homoallylic, and Bishomoallylic Alcohols with Aldehydes and<i>N</i>-Tosylimines: Insights into the Mechanism
作者:Nanna Ahlsten、Belén Martín-Matute
DOI:10.1002/adsc.200900448
日期:2009.11
alkenols followed by reaction with aldehydes or N-tosylimines catalysed by rhodiumcomplexes has been studied. The catalytically active rhodiumcomplex is formed in situ from commercially available (cyclooctadiene)rhodium(I) chloride dimer [Rh(COD)Cl]2. The tandem process affords aldol and Mannich-type products in excellent yields. The key to the success of the coupling reaction is the activation of
已经研究了烯醇的异构化,然后与铑络合物催化的醛或N-甲苯胺反应。催化活性的铑配合物是由可商购的(环辛二烯)氯化铑(I)二聚体[Rh(COD)Cl] 2原位形成的。串联过程以优异的产率提供了羟醛和曼尼希型产品。于偶联反应的成功的关键是,催化剂的活化通过与postassium叔丁醇(叔丁醇钾),这促进了催化循环通过醇盐,而不是铑的氢化物。该机制使不需要的副产物的形成最小化。该机制已被1研究1 H NMR光谱和氘标记实验。
Chiral Phosphoramide-Catalyzed Aldol Additions of Ketone Enolates. Preparative Aspects
作者:Scott E. Denmark、Robert A. Stavenger、Ken-Tsung Wong、Xiping Su
DOI:10.1021/ja984123j
日期:1999.6.1
Trichlorosilyl enolates of ketones (enoxytrichlorosilanes) were demonstrated to be highly reactive aldoladdition reagents. Trichlorosilyl enolates of cyclohexanone (E-enolate) and propiophenone (Z-enolate) reacted readily at room temperature with a wide variety of aldehydes to afford aldoladdition products in high yield and diastereoselectivity (E → syn, Z → anti). These reactions were shown to be
Aqueous Asymmetric Mukaiyama Aldol Reaction Catalyzed by Chiral Gallium Lewis Acid with Trost-Type Semi-Crown Ligands
作者:Hui-Jing Li、Hong-Yu Tian、Yan-Chao Wu、Yong-Jun Chen、Li Liu、Dong Wang、Chao-Jun Li
DOI:10.1002/adsc.200505089
日期:2005.7
generates highly effective chiral gallium Lewis acid catalysts for aqueous asymmetric aldolreactions of aromatic silyl enol ethers with aldehydes. A ligand-acceleration effect was observed. Water is essential for obtaining high diastereoselectivity and enantioselectivity. The p-phenyl substituent in aromatic silyl enol ether (2 h) plays an important role and increases the enantioselectivity up to 95%
A catalytic amount of In(OAc) 3 smoothly promoted 1,4-reduction of certain α-enones with PhSiH 3 in ethanol at ambient temperature. The intermediary enolates could be used for inter- and intramolecular aldol reactions andintramolecular Michael addition.
aldol reactions in water using a catalytic amount of diarylborinic acid have been developed. The reactions proceeded smoothly in the presence of a small amount of an anionic surfactant and a Brønsted acid. Water was the most suitable solvent, and organic solvents such as ether and dichloromethane were ineffective in this system. Use of bis(4-trifluoromethylphenyl)borinic acid gave high catalytic activity