Results 41 to 50 of about 8,043 (225)

Synthesis of Chromen[4,3-b]pyrrolidines by Intramolecular 1,3-Dipolar Cycloadditions of Azomethine Ylides: An Experimental and Computational Assessment of the Origin of Stereocontrol [PDF]

, 2015
Azomethine ylides, generated from imine-derived O-cinnamyl or O-crotonyl salicylaldeyde and α-amino acids, undergo intramolecular 1,3-dipolar cycloaddition, leading to chromene[4,3-b]pyrrolidines.
Arrieta, Ana, Barcellos, Julio C.F., Cossío Mora, Fernando Pedro, Cossío, Unai, Costa, Paulo R.R., Cózar Ruano, Abel de, Dias, Ayres G., Nájera, Carmen, Sansano, Jose M.   +8 more
core   +2 more sources

1,3-Dipolar Cycloadditions to Bicyclic Olefins. I. 1,3-Dipolar Cycloadditions to Norbornadienes [PDF]

Bulletin of the Chemical Society of Japan, 1977
Abstract The 1,3-dipolar cycloadditions of phenylglyoxylonitrile oxide, benzonitrile-N-phenylimine, or N-phenyl-C-p-nitrophenylnitrone to norbornadiene, 2,3-dicyanonorbornadiene, and 2,3-bis(methoxycarbonyl)norbornadiene give the endo-adducts, together with the exo-adducts.
Hisaji Taniguchi, Toshikazu Ikeda, Yoshihiro Yoshida, Eiji Imoto   +3 more
openaire   +1 more source

Additive-assisted regioselective 1,3-dipolar cycloaddition of azomethine ylides with benzylideneacetone

Beilstein Journal of Organic Chemistry, 2014
1,3-Dipolar cycloadditions of isatins, benzylamine and benzylideneacetones were studied to prepare a series of novel spiropyrrolidine-oxindoles – 4′-acetyl-3′,5′-diarylspiro[indoline-3,2′-pyrrolidin]-2-ones and 3′-acetyl-4′,5′-diarylspiro[indoline-3,2 ...
Chuqin Peng, Jiwei Ren, Jun-An Xiao, Honggang Zhang, Hua Yang, Yiming Luo   +5 more
doaj   +1 more source

Coinage Metal Complexes as Chiral Catalysts for 1,3-Dipolar Cycloadditions [PDF]

, 2014
In this account, we describe the experience of our research group in the implementation of chiral coinage metal complexes into the efficient enantioselective 1,3-DC of azomethine ylides derived from α-amino acids and azlactones with different ...
Nájera, Carmen, Sansano, Jose M.
core   +2 more sources

Cold Orthogonal Translation: A Psychrophilic Pyrrolysyl‐tRNA Synthetase Boosts Genetic Code Expansion in E. coli

Advanced Science, EarlyView.
ABSTRACT Orthogonal translation systems (OTSs) enable site‐specific incorporation of non‐canonical amino acids (ncAAs) and are central to genetic code expansion. Current engineering strategies typically rely on hyperstable aminoacyl tRNA synthetase (aaRS) scaffolds to tolerate destabilizing mutations required for substrate diversification.
Nikolaj G. Koch, Peter Goettig, Michael A. Nash, Juri Rappsilber, Nediljko Budisa   +4 more
wiley   +1 more source

Copper- and Silver-Catalyzed Reactions of Active Methylene Isocyanides: Facile Access to Highly Substituted Five- and Six-Membered Heterocycles. [PDF]

Chemistry
This review summarizes recent advances in copper‐ and silver‐catalyzed reactions of active methylene isocyanides for the synthesis of highly substituted five‐ and six‐membered heterocycles. Emphasis is placed on [3+n] cycloadditions, annulations, and asymmetric strategies, highlighting current limitations and future opportunities in heterocycle ...
George J, Oh K.
europepmc   +2 more sources

Hydrazones as Singular Reagents in Asymmetric Organocatalysis [PDF]

, 2016
This Minireview summarizes strategies and developments regarding the use of hydrazones as reagents in asymmetric organocatalysis, their distinct roles in nucleophile–electrophile, cycloaddition, and cyclization reactions.
Fernández Fernández, Rosario Fátima, Lassaletta, José M., Matador Martínez, Esteban, Monge Fernández, David, Retamosa Hernández, María Gracia   +4 more
core   +1 more source

Enantioselective Cycloaddition Reactions Catalyzed by BINOL-Derived Phosphoric Acids and N-Triflyl Phosphoramides: Recent Advances

Molecules, 2015
Over the last several years there has been a huge increase in the development and applications of new efficient organocatalysts for enantioselective pericyclic reactions, which represent one of the most powerful types of organic transformations.
Felix E. Held, Dominik Grau, Svetlana B. Tsogoeva   +2 more
doaj   +1 more source

Advances and Perspectives in Graphene‐Based Quantum Dots Enabled Neuromorphic Devices

Advanced Science, EarlyView.
Graphene‐based QDs are zero‐dimensional carbon nanomaterials with pronounced quantum confinement and tunable electronic structures. Herein, we summarize their synthesis strategies and functionalization methods, and highlight their functional roles and operating mechanisms in devices, as well as recent advances in neuromorphic electronics. We anticipate
Yulin Zhen, Wei Zeng, Zherui Zhao, JiYu Zhao, Ziyan Huang, Zhuo Chen, Kui Zhou, Guanglong Ding, Su‐Ting Han, Ye Zhou   +9 more
wiley   +1 more source

Cyclooctyne-based reagents for uncatalyzed click chemistry: A computational survey [PDF]

, 2009
With the goal of identifying alkyne-like reagents for use in click chemistry, but without Cu catalysts, we used B3LYP density function theory (DFT) to investigate the trends in activation barriers for the 1,3-dipolar cycloadditions of azides with various
Chenoweth, David, Chenoweth, Kimberly, Goddard, William A. III   +2 more
core   +1 more source