Thioiminoethers and thioiminocarbonates of α-amino acid esters undergo acetic acid catalysed cycloaddition reaction with N-phenylmaleimide via their 1,3-dipolar tautomers.
Asymmetric Formal [3+2] Cycloaddition Reaction of α-Aryl Isocyanoesters with<i>N</i>-Aryl Maleimides by Bifunctional Cinchona Alkaloids-Based Squaramide/AgSbF<sub>6</sub>Cooperative Catalysis
作者:Mei-Xin Zhao、Deng-Ke Wei、Fei-Hu Ji、Xiao-Li Zhao、Min Shi
DOI:10.1002/asia.201200686
日期:2012.12
better to be cooperative: A highly diastereo‐ and enantioselective asymmetric [3+2] cycloaddition reaction of α‐aryl isocyanoacetates with N‐aryl maleimides through cooperative catalysis of cinchona alkaloid‐derived squaramide/AgSbF6 was developed. A wide range of optically active, substituted 1,3a,4,5,6,6a‐hexahydropyrrolo[3,4‐c] pyrrole derivatives was obtained in highyields (up to 98 %), high diastereoselectivities
最好是协同作用:通过金鸡纳生物碱衍生的方酸酰胺/ AgSbF 6的协同催化,开发了α-芳基异氰基乙酸酯与N-芳基马来酰亚胺的高度非对映体和对映选择性不对称[3 + 2]环加成反应。以高收率(高达98%),高非对映选择性(> 20:1 dr ),并且在温和的反应条件下对映体的选择性良好(高达ee的92%)。
Au-Catalyzed Asymmetric Formal [3 + 2] Cycloaddition of Isocyanoacetates with Maleimides
作者:Silvia Padilla、Javier Adrio、Juan C. Carretero
DOI:10.1021/jo3003425
日期:2012.4.20
An efficient protocol for the Au-I-catalyzed asymmetric formal [3 + 2] cycloaddition of isocyanoacetates with phenylmaleimide has been developed. In the presence of cationic Au-I/DTBM-segphos complex, excellent diastereoselectivity and high levels of enantioselectivity (up to 97% cc) have been attained with a variety of alpha-substituted isocyanoacetates. The synthetic potential of the resulting enantioenriched 1-pyrrolines has been demonstrated by the preparation of highly substituted pyrrolidines bearing a quaternary stereocenter.
Generation of functionalized azomethine ylides and their application to stereoselective heterocycle synthesis: an equivalent process of C-unsubstituted nitrile ylide cycloaddition reaction
Abstract The synthetic process equivalent to C-unsubstituted (CH) nitrileylides cycloaddition reaction is achieved via cycloaddition of NH-azomethine ylide and the following fission reaction of the cycloadducts under acidic conditions. Cycloaddition of NH-azomethine ylide generated by a thermal 1,2-prototropy in 4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carbaldehyde system with maleimides provides proline