نتایج جستجو برای: chemoselective

تعداد نتایج: 1372  

Journal: :Organic letters 2005
Ren-Hua Fan Jihane Achkar Jesús M Hernández-Torres Alexander Wei

[reaction: see text] An orthogonal sulfation strategy involving six different protecting groups has been developed for generating sulfated carbohydrate libraries based on heparan. Chemoselective cleavage conditions (optimized for a heparan disaccharide) can be performed in the presence of sulfate esters as well as the remaining protecting groups.

Journal: :Dalton transactions 2011
Thomas Kauf Pierre Braunstein

The reaction of TCNE and TCNQ zwitterionic benzoquinonemonoimine derivatives under basic conditions resulted in HCN elimination to give a tricyanoethenyl derivative - which forms a π-complex with Pd(0)--or a stable malodinitrile salt, respectively. In the latter case, chemoselective C-alkylation was observed whereas oxidation led to dimerization by C-C coupling.

Journal: :Dalton transactions 2018
Hsiu-Jung Lin Sean Lutz Catherine O'Kane Matthias Zeller Chun-Hsing Chen Talal Al Assil Wei-Tsung Lee

A low-coordinate iron(ii) complex (CztBu(PztBu)2)Fe[N(SiMe3)2], 1 bearing an NNN-pincer ligand was prepared and fully characterized. Intramolecular C-H activation on the 5-position of a pyrazole at elevated temperatures was observed. Complex 1 was found to be an efficient and chemoselective pre-catalyst for the hydrosilylation of organo carbonyl substrates.

2014
Oleg Melnyk Nathalie Ollivier Soizic Besret Patricia Melnyk

The design of novel chemoselective and site-specific ligation methods provides new tools for obtaining complex scaffolds, peptidomimetics, and peptide conjugates. The chemistry of the N-phenylthiocarbonyl group has led to several developments in peptide ligation chemistry and peptide bioconjugation during the last 10 years. The aim of this review is to provide an overview of this emerging field.

2017
Jing Leng Shi-Meng Wang Hua-Li Qin

A highly efficient and chemoselective method for the synthesis of diaryl disulfides is developed via a visible light-promoted coupling of readily accessible arenediazonium tetrafluoroborates and CS2. This practical and convenient protocol provides a direct pathway for the assembly of a series of disulfides in an environmentally friendly manner with good to excellent yields.

Journal: :Chemical communications 2012
Abhishek Dutta Chowdhury Goutam Kumar Lahiri

Fe(BF(4))(2)·6H(2)O in the presence of pyridine-2,6-dicarboxylic acid and PhI(OAc)(2) can efficiently catalyze the formation of chemoselective dialkyl acetals from styrene derivatives with anti-Markovnikov regioselectivity in good to high yields under mild and benign reaction conditions.

Journal: :Dalton transactions 2010
Malay Patra Gilles Gasser Dmytro Bobukhov Klaus Merz Alexander V Shtemenko Nils Metzler-Nolte

In the view of developing a synthetic route for the controlled insertion of distinct organometallic moieties into peptide nucleic acid (PNA) oligomers, a proof-of-principle study of the chemoselective insertion of three different organometallics into a building block containing both a PNA backbone and an alkyne side-chain is presented in this study.

Journal: :Angewandte Chemie 2013
Nathan T Jui Stephen L Buchwald

By choice: The palladium-catalyzed cascade reaction of 2-chloroaryl sulfonates with arylamine and amide nucleophiles provides direct access to N-arylbenzimidazoles. This strategy selectively produces the heterocycles based on chemoselective oxidative addition. 2-Chloroaryl triflates (Tf) produce one regioisomer and the corresponding 2-chloroaryl mesylates (Ms) deliver the other in a selectable ...

Journal: :Chemical communications 2012
Xin Ma Wanfang Li Xiaoming Li Xiaoming Tao Weizheng Fan Xiaomin Xie Tahar Ayad Virginie Ratovelomanana-Vidal Zhaoguo Zhang

Finely-tuned ruthenium-catalyzed highly chemoselective and enantioselective hydrogenation of γ-halo-γ,δ-unsaturated-β-keto esters at the carbonyl group was achieved under neutral reaction conditions (ee up to 97%). Both olefin and alkenyl halogen moieties, which are labile under hydrogenation conditions, remained untouched during the reaction.

Journal: :Chemical communications 2014
Zen Maeno Takato Mitsudome Tomoo Mizugaki Koichiro Jitsukawa Kiyotomi Kaneda

The selective synthesis of the [Rh5(CO)15](-) cluster within the PPI dendrimer was successfully demonstrated. The dendrimer-encapsulated [Rh5(CO)15](-) was resistant to decomposition under the catalytic reaction conditions and exhibited extremely high selectivity for the chemoselective reduction of nitro groups of various nitro aromatics with other reducible groups using CO/H2O as a reductant.

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