Enantioselective conjugate addition of pyrazolones to nitroalkenes catalyzed by chiral squaramide organocatalyst
作者:Alime Ebru Aydin、Selda Culha
DOI:10.1002/chir.23295
日期:2021.3
squaramide catalysts (8–15) were synthesized, and their catalytic efficiency in the enantioselectiveconjugateaddition of pyrazolones to nitroalkenes was described. This protocol provides excellent chemical yields (up to 93%) of chiral 5‐methyl‐4‐(2‐nitro‐1‐arylethyl)pyrazol‐3‐ol derivatives with high enantioselectivities (up to 97% ee).
Rapid chiral assay of amino compounds using diethyl squarate
作者:Jun Tian、Yi-Xuan Jiang、Xiao-Qi Yu、Shan-Shan Yu
DOI:10.1016/j.saa.2022.120871
日期:2022.5
importance of chiralcompounds make it urgent to develop fast and efficient methods to detect the absolute configuration, enantiomeric excess(ee), and concentration of chiralcompounds. In this study, we demonstrate that commercially available diethyl squarate can rapidly react with various types of chiral amino compounds and exhibit characteristic ultraviolet (UV) and circular dichroism (CD) signals.
手性化合物的多功能性和重要性使得开发快速有效的方法来检测绝对构型、对映体过量(ee) 和手性化合物的浓度。在这项研究中,我们证明了市售的方酸二乙酯可以与各种类型的手性氨基化合物快速反应,并表现出特征性的紫外 (UV) 和圆二色性 (CD) 信号。UV 和 CD 信号可以分别确定两种对映体的总浓度和样品的 ee 值。该探针显示出广泛的底物范围,适用于 39 种测试的手性氨基化合物,包括手性氨基酸、氨基醇和胺。此外,该探针准确检测了10个苯丙氨酸、苯基甘氨醇和苯乙胺样品,误差范围小于8%,证明了该方法的实用性。
Organocatalyzed Enantioselective Allylation of Isatins by Using a Chiral Amino Alcohol Derived Squaramide as Catalyst
作者:Debashis Ghosh、Naveen Gupta、Sayed H. R. Abdi、Sekhar Nandi、Noor-ul H. Khan、Rukhsana I. Kureshy、Hari C. Bajaj
DOI:10.1002/ejoc.201500155
日期:2015.5
3,4-dimethoxycyclobut-3-ene-1,2-dione in two steps. A 2.5 mol-% loading of the organocatalyst successfully catalyzed the asymmetric allylation of isatins with allyltributyltin to give the corresponding 3-allyl-3-hydroxyoxindoles in high yields and enantioselectivities (up to 98 % ee).
Design, synthesis and structure of new chiral squaric acid monoaminoalcohols and diaminoalcohols and their use as catalysts in asymmetric reduction of ketones and diketones
Many chiral squaricacid aminoalcohols and C2-symmetric diaminoalcohols have been synthesized and their in situ formed chiral boron heterocycles have been used as catalysts for the enantioselective reduction of prochiral ketones and diketones by borane to give alcohols with up to 99% enantiomeric excess and 99% yield. The effects of solvent, catalyst–substrate ratio and temperature were also investigated