Efficient Palladium-catalyzed Suzuki–Miyaura reactions using phenolic Schiff base ligands under ambient conditions in aqueous media

2013 ◽  
Vol 38 (4) ◽  
pp. 401-405 ◽  
Author(s):  
Zhonggao Zhou ◽  
Zhenyun Zhou ◽  
Aichen Chen ◽  
Xiuhua Zhou ◽  
Qi Qi ◽  
...  
Keyword(s):  
Schiff Base ◽  
Aqueous Media ◽  
Ambient Conditions ◽  
Schiff Base Ligands ◽  
Palladium Catalyzed

scholarly journals Unprecedented Water Effect as a Key Element in Salicyl-Glycine Schiff Base Synthesis

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1257 ◽  
Author(s):  
Karolina Bakalorz ◽  
Łukasz Przypis ◽  
Mateusz Michał Tomczyk ◽  
Maria Książek ◽  
Ryszard Grzesik ◽  
...  
Keyword(s):  
Schiff Base ◽  
Aqueous Media ◽  
Schiff Base Ligands ◽  
Metal Catalysis ◽  
Space Groups ◽  
Monoclinic Form ◽  
Metal Organic ◽  
And Behavior ◽  
Amino Acid Schiff Base

Salens, as chelating, double Schiff base ligands, are an important group utilized in transition metal catalysis. They have been used to build interesting functional metal-organic frameworks (MOFs). However, salens interacting with amino acids have also found applications in receptors. Here, we intended to form a “green” glycine-derived salen fragment, but the available literature data were contradictory. Therefore, we optimized the synthetic conditions and obtained the desired product as two different crystallographic polymorphs (orthorhombic Pcca and monoclinic P21/c space groups). Their structures differ in conformation at the glycine moiety, and the monoclinic form contains additional, disordered water molecules. Despite the high stability of Schiff bases, these newly obtained compounds hydrolyze in aqueous media, the process being accelerated by metal cations. These studies, accompanied by mechanistic considerations and solid-state moisture and thermal analysis, clarify the structure and behavior of this amino acid Schiff base and shed new light on the role of water in its stability.

scholarly journals Synthesis of Metal-Coordinating Arenediynes And Study Of Their Reactivity in Bergman Cyclization

2021 ◽  
Author(s):  
Salma. Al-Karmi
Keyword(s):  
Schiff Base ◽  
High Temperature ◽  
Energy Barrier ◽  
Room Temperature ◽  
Antitumor Agents ◽  
Endothermic Reaction ◽  
Bergman Cyclization ◽  
Ambient Conditions ◽  
Schiff Base Ligands ◽  
Bergman Cycloaromatization

The Bergman cycloaromatization (BC) in which a cis-alkene-1,2-diyne (enediyne) cyclizes to form a p-benzyne diradical, typically is a very endothermic reaction, requiring a substantial amount of energy (i.e. high temperature) for it to proceed. This reaction received very little attention until a decade after its discovery, when the natural enediynes were isolated and shown to be the most active antitumor agents every discovered. Having BC at the heart of their mode of action, these natural enediynes have been very challenging to mimic from synthetic standpoints. Of particular interest is to be able to design and synthesize an enediyne that is stable at room temperature, while also being capable of being triggered to undergo BC under ambient conditions. Although a relatively new concept, metal-induced BC reactions have generally been known to decrease the demanding energy barrier. The work presented here describes several synthetic strategies towards arenediyne crown eithers and the synthesis of several arenediyne hydrazone/Schiff base ligands with extended n-systems. These synthesized enediynes are useful ligands, capable of metal-cordination and hence potentially decreasing the BC energy barrier. BC reactions of enediyne intermediates are also reported.

scholarly journals Synthesis of Metal-Coordinating Arenediynes And Study Of Their Reactivity in Bergman Cyclization

2021 ◽  
Author(s):  
Salma. Al-Karmi
Keyword(s):  
Schiff Base ◽  
High Temperature ◽  
Energy Barrier ◽  
Room Temperature ◽  
Antitumor Agents ◽  
Endothermic Reaction ◽  
Bergman Cyclization ◽  
Ambient Conditions ◽  
Schiff Base Ligands ◽  
Bergman Cycloaromatization

The Bergman cycloaromatization (BC) in which a cis-alkene-1,2-diyne (enediyne) cyclizes to form a p-benzyne diradical, typically is a very endothermic reaction, requiring a substantial amount of energy (i.e. high temperature) for it to proceed. This reaction received very little attention until a decade after its discovery, when the natural enediynes were isolated and shown to be the most active antitumor agents every discovered. Having BC at the heart of their mode of action, these natural enediynes have been very challenging to mimic from synthetic standpoints. Of particular interest is to be able to design and synthesize an enediyne that is stable at room temperature, while also being capable of being triggered to undergo BC under ambient conditions. Although a relatively new concept, metal-induced BC reactions have generally been known to decrease the demanding energy barrier. The work presented here describes several synthetic strategies towards arenediyne crown eithers and the synthesis of several arenediyne hydrazone/Schiff base ligands with extended n-systems. These synthesized enediynes are useful ligands, capable of metal-cordination and hence potentially decreasing the BC energy barrier. BC reactions of enediyne intermediates are also reported.

Conductivity Studies of Schiff Base Ligands Derived from O-Phenylenediamine and Their Co(II) and Zn(II) Complexes

2015 ◽  
Vol 12 (2) ◽  
pp. 13
Author(s):  
Muhamad Faridz Osman ◽  
Karimah Kassim
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Schiff Base ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Impedance Spectroscopy ◽  
Ftir Spectroscopy ◽  
Coordination Complexes ◽  
Frequency Range ◽  
Schiff Base Ligands

The coordination complexes of Co(II) and Zn(II) with Schiff bases derived from o-phenylenediamine and substituted 2-hydroxybenzaldehyde were prepared All compounds were characterized by Fourier transform infrared (FTIR) spectroscopy and Nuclear magnetic resonance (NMR) spectroscopy elemental analyzers. They were analyzed using impedance spectroscopy in the frequency range of 100Hz-1 MHz. LI and L2 showed higher conductivity compared to their metal complexes, which had values of 1.3 7 x 10-7 and 6.13 x 10-8 S/cm respectively. 

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