Asymmetric synthesis of functionalized 2,3-dihydrobenzofurans using salicyl N-phosphonyl imines facilitated by group-assisted purification (GAP) chemistry
Group-Assisted Purification Chemistry for Asymmetric Mannich-type Reaction of Chiral <i>N</i>-Phosphonyl Imines with Azlactones Leading to Syntheses of α-Quaternary α,β-Diamino Acid Derivatives
作者:Haowei Zhang、Zhen Yang、Brian Nlong Zhao、Guigen Li
DOI:10.1021/acs.joc.7b02556
日期:2018.1.19
An asymmetric Mannich-type reaction between chiral N-phosphonyl imines and azlactones [oxazol-5(4H)-ones] has been established under convenient conditions at room temperature. The reaction was performed without using any bases, additives, or catalysts to achieve up to excellent chemical yields and diastereoselectivity for 32 examples. The α-quaternary syn-α,β-diamino acid products were purified simply
of new chiral N -phosphinyl β-enamino esters and amides were successfully prepared with excellent Z -stereoselectivity ( Z / E > 99:1 in nearly all cases). Group-assisted purification chemistry proved to be an efficient method for the asymmetric reduction of the resulting β-enamino esters/amides to give enantiopure β-amino esters/amides. The asymmetric reduction can be controlled efficiently by using
Asymmetric [3 + 2] Cycloaddition of Chiral <i>N</i>-Phosphonyl Imines with Methyl Isocyanoacetate for Accessing 2-Imidazolines with Switchable Stereoselectivity
作者:Shuo Qiao、Cody B. Wilcox、Daniel K. Unruh、Bo Jiang、Guigen Li
DOI:10.1021/acs.joc.6b03068
日期:2017.3.17
Asymmetric [3 + 2] cycloaddition of chiral N-phosphonyl imines with methyl isocyanoacetate has been established, enabling controllable/switchable stereoselectivity access to 21 examples of cycloadducts with good to excellent chemical yields (up to 92%) and high diastereoselectivities (up to 99:1 dr). The cycloadditionreaction promoted by Cs2CO3 resulted in diastereoenriched (4R,5S)-products with >99:1
Asymmetric [4 + 2] cycloaddition synthesis of 4<i>H</i>-chromene derivatives facilitated by group-assisted-purification (GAP) chemistry
作者:Hossein Rouh、Yao Tang、Sai Zhang、Ahmed I. M. Ali、Kazimierz Surowiec、Daniel Unruh、Guigen Li
DOI:10.1039/d1ra08323f
日期:——
preparation of functionalized 4H-chromene derivatives via a Cs2CO3-catalyzed [4 + 2] cycloaddition of enantiopure chiral salicyl N-phosphonyl imines with allenoates. Fifteen examples were achieved in excellent yields and diastereoselectivity. The products were purified simply by washing the crude mixture with hexanes following the Group-Assisted Purification (GAP) chemistry/technology to bypass traditional
在这项工作中,我们提出了一种通过Cs 2 CO 3催化的 [4 + 2] 对映纯手性水杨基 N-膦酰基亚胺与烯丙酸酯的环加成来制备功能化 4 H-色烯衍生物的策略。十五个实例以优异的产率和非对映选择性实现。产品经过简单的纯化,即按照基团辅助纯化 (GAP) 化学/技术用己烷洗涤粗混合物以绕过传统的分离方法。绝对构型由 X 射线结构分析明确确定。
Asymmetric synthesis of homoallylic amines via 1,2-addition of Grignard reagent to aliphatic N-phosphonyl hemiaminal
作者:Shuo Qiao、Suresh Pindi、Preston T. Spigener、Bo Jiang、Guigen Li
DOI:10.1016/j.tetlet.2015.12.106
日期:2016.2
A general method for asymmetricsynthesis of alkylated homoallylic amines was developed via a one-potthree-componentreaction of easily available N-phosphonyl amides, aliphatic aldehydes, and allylic Grignard reagents. As anticipated the reaction proceeds through six-membered chelation controlled mechanism, allowing 1,2-nucleophilic addition to directly give chiral homoallylic amines with high yields