Silver-Catalyzed Asymmetric Desymmetrization of Cyclopentenediones via [3 + 2] Cycloaddition with α-Substituted Isocyanoacetates
作者:Jimil George、Hun Young Kim、Kyungsoo Oh
DOI:10.1021/acs.orglett.8b00590
日期:2018.4.20
A highly selective and practical asymmetric Ag(I) catalyst system has been developed for the [3 + 2] cycloaddition reactions between isocyanoacetates and cyclopentenediones. The current Ag(I) catalyst system tolerates moisture and air and readily utilizes class III solvents such as EtOAc and acetone. The development of on demand generation of an active chiral catalyst in the presence of isocyanides
Some work leading to syntheses of oestrone is presented. It was generally found necessary to protect the 1-carbonyl function in 5,6,7,7a-tetrahydro-8β-methylindane-1,5-dione before the introduction of alkyl groups at position 4. Alkylations of 2-methylcyclopentane-1,3-dione have been made and the results compared with similar studies on 2-methylcyclohexane-1,3-dione.
We present herein an unprecedented desymmetrization of meso 1,3-diones by enantioselective intermolecular condensation. Under the catalysis by a chiral phosphoric acid, a range of readily available 1,3-diones undergo reaction with hydrazines to produce cyclic and acyclic keto-hydrazones bearing an all-carbon quaternary center in high efficiency and enantioselectivity. These compounds are also highly
Chiral Phosphoric Acid Catalyzed Desymmetrization of Cyclopentendiones via Friedel–Crafts Conjugate Addition of Indolizines
作者:Qijian Ni、Zhiming Zhu、Yanjun Fan、Xiaoyun Chen、Xiaoxiao Song
DOI:10.1021/acs.orglett.1c03780
日期:2021.12.17
An organocatalytic highly diastero- and enantioselective Friedel–Crafts conjugate addition of indolizines to prochiral cyclopentenediones has been successfully developed. This desymmetric transformation provides a direct access to the desired indolizine-substituted cyclopentanediones in yields of 62–91% and excellent stereoselectivities. The utility of the approach was demonstrated by diverse late-stage
Desymmetrization of cyclic 1,3-diketones <i>via</i> Ir-catalyzed hydrogenation: an efficient approach to cyclic hydroxy ketones with a chiral quaternary carbon
作者:Quan Gong、Jialin Wen、Xumu Zhang
DOI:10.1039/c9sc01769k
日期:——
We herein report an efficient method to synthesize cyclic hydroxy ketones with a chiral quaternary center. Catalyzed by an Ir/f-ampha complex, cyclic α,α-disubstituted 1,3-diketones were hydrogenated, giving mono-reduced products with both high enantioselectivities and diastereoselectivities. In addition, CC and CC bonds could survive in this catalytic system. This method was applied in the preparation
我们在此报告了一种合成具有手性季铵中心的环状羟基酮的有效方法。在 Ir/f-ampha 配合物的催化下,环状 α,α-二取代 1,3-二酮被氢化,得到具有高对映选择性和非对映选择性的单还原产物。此外,C C 和 C C 键可以在该催化体系中存活。该方法用于制备(+)-雌酮。在这种化学转化中没有观察到二醇。由于空间位阻,实现了对映异构体和非对映异构体的诱导。