由手性膦BINAP容易制备的手性膦氧化物BINAPO在三氯甲硅烷基化合物通过高价硅酸盐中间体的反应中表现出良好的催化活性。在催化量的BINAPO存在下,醛与烯丙基三氯硅烷的烯丙基化反应使烯丙基化的加合物具有良好的对映选择性(最高79%ee),其中二异丙基乙胺和四丁基碘化铵作为添加剂的组合对于加速催化循环至关重要。31氧化膦的1 P NMR分析表明,胺促进了氧化膦从硅原子上的解离。BINAPO还促进了二异丙基乙胺作为添加剂存在下醛与三氯甲硅烷基烯醇醚的对映体选择性醛醇缩合反应,从而以高非对映体和对映体选择性(最高syn / anti = 1 / 25,96%ee(anti))提供了相应的醛醇加合物。)。
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
The Chemistry of Trichlorosilyl Enolates. 2. Highly-Selective Asymmetric Aldol Additions of Ketone Enolates
作者:Scott E. Denmark、Ken-Tsung Wong、Robert A. Stavenger
DOI:10.1021/ja9636698
日期:1997.3.1
problem, namely, the invention/discovery of asuitable chiral Lewis acid catalyst to effect the reaction betweenan enoxysilane derivative and an aldehyde, Scheme 1 (X ) Me).In a recent Communication we have described a conceptuallydistinct approach which employs chiral Lewis bases (phos-phoramides) in combination with trichlorosilyl enolates, Scheme1(X)Cl).
Highly enantioselective synthesis of syn-aldols of cyclohexanones via chiral primary amine catalyzed asymmetric transfer aldol reactions in ionic liquid
作者:Pengxin Zhou、Sanzhong Luo、Jin-Pei Cheng
DOI:10.1039/c0ob00682c
日期:——
Chiral primary-tertiary diamine/TfOH was found to catalyze kinetic resolution of racemic syn-aldols of cyclohexanones in ionicliquid effectively, affording the chiral syn-aldols with up to 99 : 1 syn/anti and 99% ee.
A catalytic amount of KF.18-crown-6 complex is effective as a soluble fluoride source to activate an asymmetric Sakurai-Hosomi allylation with BINAP and silver(I) triflate catalyst. The allylation of a variety of aromatic, alpha,beta-unsaturated and aliphatic aldehydes with allylic trimethoxysilane resulted in high yields and remarkable enantioselectivities. In addition, the asymmetric Mukaiyama-type
of a catalytic amount of tributyltin methoxide and stoichiometric amount of MeOH to give an aldol adduct. Methanolysis of the in situ generating tin alkoxide of aldol adduct regenerates the tinmethoxide, and thus the aldolreaction can proceed catalytically. The use of BINAP·silver(I) complex as an additional catalyst results in formation of optically active aldol products. This catalytic method has