Lastereomutation autour de la double liaison partielle d'une serie de cations methoxy-1- et hydroxy-1 aryl-3 allyles est Examee Experimentalement dans dessolutions d'acides forts et theoriquement en utilisant les calculs HF/STO-36
Nickel(II)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions with carboxylic acid derivatives
作者:Pengbo Ye、Xuan Liu、Gang Wang、Lei Liu
DOI:10.1016/j.cclet.2020.08.034
日期:2021.3
A nickel(II)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions generated in situ from corresponding acetals with carboxylic acid derivatives to prepare β-alkoxyl carbonyl moieties with diverse α-substituents has been disclosed. The method exhibited broad scope of acetals and carboxylic acid derivatives with excellent enantioselectivity and good functional group compatibility, and can be
The use of 1,2-O-isopropylidene-α-d-xylofuranose as a chiral auxiliary in asymmetric cyclopropanation reactions
作者:José M. Vega-Pérez、Ignacio Periñán、Fernando Iglesias-Guerra
DOI:10.1016/j.tetasy.2009.02.062
日期:2009.5
1,2-O-isopropylidene-d-xylofuranose, as a chiralauxiliary, is described. The Simmons–Smith cyclopropanationreaction of the corresponding alkenylidene derivatives with CH2I2/ZnEt2, in different reaction conditions, took place with high stereoselectivity. The diastereomeric excess in each case depended on the solvent and the temperature used in the reaction. The absolute configuration of the new stereogenic
描述了衍生自作为手性助剂的1,2 - O-异亚丙基-d-木呋喃糖的环丙基亚甲基缩醛的立体选择性合成。在不同的反应条件下,相应的链烯基衍生物与CH 2 I 2 / ZnEt 2的Simmons-Smith环丙烷化反应具有很高的立体选择性。在每种情况下,非对映异构体过量取决于反应中所用的溶剂和温度。通过手性助剂的环丙烷部分的酸水解确定了形成的新的立体异构中心的绝对构型,该手性助剂也被回收了。
Highly Enantioselective Azadiene Diels−Alder Reactions Catalyzed by Chiral N-Heterocyclic Carbenes
作者:Ming He、Justin R. Struble、Jeffrey W. Bode
DOI:10.1021/ja062707c
日期:2006.7.1
Highly enantioselective, N-heterocyclic carbene (NHC)-catalyzed aza-Diels-Alder reactions are described. A novel chiral triazolium salt based on the cis-1,2-aminoindanol platform serves as an efficient precatalyst for the NHC-catalyzed redox generation of enolate dienophiles that undergo LUMOdiene-controlled Diels-Alder reactions with N-sulfonyl-alpha,beta-unsaturated imines in good yields and with exceptional diastereo- and enantioselectivities (>99% ee). In contrast to uncatalyzed variants, this organocatalytic process proceeds at room temperature without stoichiometric reagents, producing synthetically valuable, enantiomerically pure cis-3,4-disubstituted dihydropyridinone products.
ZEBOVITZ T. C.; HECK R. F., J. ORG. CHEM., 1977, 42, NO 24, 3907-3909