نتایج جستجو برای: azomethine ylides

تعداد نتایج: 1359  

Journal: :Chemical communications 2014
Qi-Liang Yang Ming-Sheng Xie Chao Xia Huan-Li Sun Dan-Jie Zhang Ke-Xin Huang Zhen Guo Gui-Rong Qu Hai-Ming Guo

A rapid and divergent access to chiral azacyclic nucleoside analogues has been established via highly exo-selective and enantioselective 1,3-dipolar cycloaddition of azomethine ylides with β-nucleobase substituted acrylates. Using 1 mol% of a chiral copper complex, various chiral azacyclic nucleoside analogues were obtained in high yields, excellent exo-selectivities and enantioselectivities (9...

Journal: :Chemical communications 2014
Enrique E Maroto Marta Izquierdo Michihisa Murata Salvatore Filippone Koichi Komatsu Yasujiro Murata Nazario Martín

A complete stereocontrol of 1,3-dipolar cycloaddition of N-metalated azomethine ylides onto endohedral fullerene H2@C60 is reported for the first time. The stereodivergent synthesis of either the cis or the trans endohedral cycloadduct is achieved with excellent diastereo- and enantioselectivities.

Journal: :Chemical communications 2015
Cong-Shuai Wang Ren-Yi Zhu Yu-Chen Zhang Feng Shi

A chemoselective [3+3] cycloaddition of in situ generated azomethine ylides with quinone monoimides has been established, which efficiently led to the construction of dihydrobenzoxazine frameworks with biological relevance, with excellent chemoselectivities and high yields (up to >95 : 5 cr and 98% yield).

2016
Manjunatha Narayanarao Lokesh Koodlur Vijayakumar G Revanasiddappa Subramanya Gopal Susmita Kamila

A new series of spiropyrrolidine compounds containing indole/indazole moieties as side chains have been accomplished via a one-pot multicomponent synthesis. The method uses the 1,3-dipolar cycloaddition reaction between N-alkylvinylindole/indazole and azomethine ylides, prepared in situ from cyclic/acyclic amino acids. The 1,3-dipolar cycloaddition proceeds efficiently under thermal conditions ...

2007
Wei Zeng Yong-Gui Zhou

Ferrocene derived P,S-heterodonor ligands were effectively used in AgOAc catalyzed asymmetric cycloaddition of azomethine ylides. The roles of planar chirality and electronic properties of the phosphorous substituents have been examined, and up to 93% ee was obtained. 2007 Elsevier Ltd. All rights reserved. The 1,3-dipolar cycloaddition reaction has become a powerful synthetic tool, providing a...

Journal: :Molecules 2012
Zhibin Huang Qian Zhao Gang Chen Huiyuan Wang Wei Lin Lexing Xu Hongtao Liu Juxian Wang Daqing Shi Yucheng Wang

A series of novel dispirooxindoles have been synthesized through three-component 1,3-dipolar cycloaddition of azomethine ylides generated in situ by the decarboxylative condensation of isatin and an α-amino acid with the dipolarophile 5-benzylidene-1,3-dimethylpyrimidine-2,4,6-trione. This method has the advantages of mild reaction conditions, high atom economy, excellent yields, and high reg...

Journal: :Journal of the American Chemical Society 2013
Michael A Ischay Michael K Takase Robert G Bergman Jonathan A Ellman

Acid treatment of densely substituted 2-silyl-1,2-dihydropyridines provides a new and convenient entry to reactive azomethine ylides that can (1) be protonated and reduced with high stereoselectivity to give piperidines, (2) participate in [3 + 2] dipolar cycloaddition to give tropanes, and (3) undergo a Nazarov-like 6-π electrocyclization that upon reduction give 2-azabicyclo[3.1.0] systems.

Journal: :Organic & biomolecular chemistry 2009
Carmen Nájera José M Sansano

In the present perspective the advances and real possibilities of 1,3-dipolar cycloadditions as key steps in the total synthesis of virus inhibitors are described. Azides, nitrones, and azomethine ylides are the most appropriate 1,3-dipoles for the synthesis of privileged structures with the highest biological responses against viruses.

Journal: :Current topics in medicinal chemistry 2014
Carmen Nejera Jose M Sansano

This review highlights the biological importance of many polysubstituted nitro-prolines and -pyrrolidines. Their preparation using asymmetric 1,3-dipolar cycloadditions of azomethine ylides with nitroalkenes using diastereoselective and enantioselective strategies is described remarking the scope and main features of each one.

2014
Qin Xu De Wang Yin Wei Min Shi

A highly regio- and stereoselective synthesis of bispirooxindoles by 1,3-dipolar cycloaddition of in situ generated azomethine ylides from isatin and proline to different electron-deficient alkenes has been developed. The synthesis affords the desired bispiro scaffold compounds in excellent yields with high regioselectivity under mild conditions. The stereochemistry was determined by single-cry...

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