نتایج جستجو برای: symmetric catalyst

تعداد نتایج: 124781  

Journal: :Chemical science 2017
Xue Xu Yong Wang Xin Cui Lukasz Wojtas X Peter Zhang

For the first time, α-formyldiazoacetates have been successfully applied for the asymmetric cyclopropanation of alkenes via Co(ii)-based metalloradical catalysis. The cobalt(ii) complex of the D2-symmetric chiral amidoporphyrin [Co(3,5-Di t Bu-ChenPhyrin)] is an effective metalloradical catalyst that can activate α-formyldiazoacetates to cyclopropanate both aromatic and aliphatic olefins with v...

Journal: :Chemistry 2008
Sascha Jautze Paul Seiler René Peters

The development of the first highly active enantioselective catalyst for the aza-Claisen rearrangement of Z-configured allylic trifluoroacetimidates generating valuable almost enantiopure protected allylic amines is described. Usually Z-configured allylic imidates react significantly slower than their E-configured counterparts, but in the present study the opposite effect was observed. Z-Config...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2006
Vincenzo Busico Roberta Cipullo Roberta Pellecchia Sara Ronca Giuseppina Roviello Giovanni Talarico

After five decades of largely serendipitous (albeit formidable) progress, catalyst design in Ziegler-Natta olefin polymerization, i.e., the rational implementation of new active species to target predetermined polyolefin architectures, has ultimately become a realistic ambition, thanks to a much deeper fundamental understanding and major advances in the tools of computational chemistry. In this...

Journal: :Yakugaku zasshi : Journal of the Pharmaceutical Society of Japan 2003
Kazuo Nagasawa

Crambescidins and batzelladines, novel marine guanidine alkaloids, have unique pentacyclic and tricyclic guanidine core structures, respectively. They display a considerable array of biological activity and not surprisingly have attracted considerable synthetic interest. The first total synthesis of crambescidin 359 (7) and stereoselective total synthesis of batzelladine D (11) were accomplishe...

Journal: :sahand communications in mathematical analysis 0
mohammad hossein sattari department of mathematics, faculty of science, azarbaijan shahid madani university, p.o.box 53751-71379, tabriz, iran. hamid shafieasl department of mathematics, faculty of science, azarbaijan shahid madani university, p.o.box 53751-71379, tabriz, iran.

in this paper we introduce two symmetric variants of amenability, symmetric module amenability and symmetric connes amenability. we determine symmetric module amenability and symmetric connes amenability of some concrete banach algebras. indeed, it is shown that $ell^1(s)$ is  a symmetric $ell^1(e)$-module amenable if and only if $s$ is amenable, where $s$ is an inverse semigroup with subsemigr...

Journal: :Chem catalysis 2022

In this issue of Chem Catalysis, Wang et al. report the synthesis 1,1-cyclopropanediesters promoted by a D2-symmetric chiral amidoporphyrin catalyst. The carbene transfer from unsymmetrical diazomalonates to large scope challenging alkenes occurred with high stereocontrol thanks efficiency Co(II)-based metalloradical catalytic system.

2017
Frédéric Hapiot Eric Monflier

Aqueous biphasic catalysis is a convenient approach to convert organic, partially soluble molecules in water. However, converting more hydrophobic substrates is much more challenging as their solubility in water is extremely low. During the past ten years, substantial progress has been made towards improving the contact between hydrophobic substrates and a hydrophilic transition-metal catalyst....

1997
Ana Jurema Maureen O'Rourke

This paper argues that Information Technology (IT) needs to be demystified, through critical consciousness, for educators to focus on IT as a means to enhance learning. It goes on to define the technical, sociohistorical and political-ideological levels of IT and to identify four theoretical constructs: tutorial, machine-as-human, tool kit and catalyst. Pervading these constructs is the underst...

2016
Veronica Paradiso Sergio Menta Marco Pierini Giorgio Della Sala Alessia Ciogli Fabia Grisi

In order to design improved chiral ruthenium catalysts for asymmetric olefin metathesis, enantiomeric catalysts incorporating C1-symmetric N-Heterocyclic carbenes (NHC) ligands with syn-related substituents on the backbone were synthesized starting from meso-1,2-diphenylethylenediamine. The absolute configuration of the enantiomers of the desymmetrized meso diamine was assigned by optical rotat...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید