scholarly journals Learning from B12 enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

2018 ◽  
Vol 14 ◽  
pp. 2553-2567 ◽  
Author(s):  
Keishiro Tahara ◽  
Ling Pan ◽  
Toshikazu Ono ◽  
Yoshio Hisaeda
Keyword(s):  
Organic Synthesis ◽  
Reaction Mechanisms ◽  
Catalytic Reactions ◽  
Vitamin B ◽  
Catalytic Systems ◽  
New Approach ◽  
Enzyme Functions

Cobalamins (B12) play various important roles in vivo. Most B12-dependent enzymes are divided into three main subfamilies: adenosylcobalamin-dependent isomerases, methylcobalamin-dependent methyltransferases, and dehalogenases. Mimicking these B12 enzyme functions under non-enzymatic conditions offers good understanding of their elaborate reaction mechanisms. Furthermore, bio-inspiration offers a new approach to catalytic design for green and eco-friendly molecular transformations. As part of a study based on vitamin B12 derivatives including heptamethyl cobyrinate perchlorate, we describe biomimetic and bioinspired catalytic reactions with B12 enzyme functions. The reactions are classified according to the corresponding three B12 enzyme subfamilies, with a focus on our recent development on electrochemical and photochemical catalytic systems. Other important reactions are also described, with a focus on radical-involved reactions in terms of organic synthesis.

Bioinspired catalytic reactions with vitamin B12 derivative and photosensitizers

2013 ◽  
Vol 85 (7) ◽  
pp. 1415-1426 ◽  
Author(s):  
Yoshio Hisaeda ◽  
Keishiro Tahara ◽  
Hisashi Shimakoshi ◽  
Takahiro Masuko
Keyword(s):  
Titanium Dioxide ◽  
Human Serum Albumin ◽  
Green Chemistry ◽  
Catalytic Reactions ◽  
Vitamin B ◽  
Hybrid Catalyst ◽  
Combined System ◽  
Catalytic Systems ◽  
Radical Intermediates ◽  
Ru Complex

As part of a study directed toward design of good catalytic systems based upon a hydrophobic vitamin B12, heptamethyl cobyrinate perchlorate, we describe the preparation of various nanomaterials using the vitamin B12 derivative and photosensitizers. Examples include vitamin B12-hyperbranched polymers (HBPs), human serum albumin (HSA) containing vitamin B12 derivatives, a vitamin B12-titanium dioxide hybrid catalyst, a vitamin B12-Ru complex combined system, and a vitamin B12-rose bengal combined system. These bioinspired materials have the potential as catalytic systems for the degradation of organic halide pollutants and for molecular transformations via radical intermediates during irradiation by UV or visible light, and offer a variety of applications that are of great interest in terms of green chemistry.

scholarly journals Dual-Catalytic Transition Metal Systems for Functionalization of Unreactive Sites of Molecules

2018 ◽  
Author(s):  
Dawid Lichosyt ◽  
Yang Zhang ◽  
Karolina Hurej ◽  
Pawel Dydio
Keyword(s):  
Transition Metal ◽  
Organic Synthesis ◽  
Functional Group ◽  
Aliphatic Alcohols ◽  
Catalytic Reactions ◽  
Allylic Alcohols ◽  
Catalytic Systems ◽  
Mild Conditions ◽  
Broad Scope ◽  
Activation Cycle

<b>Catalytic reactions occur readily at sites of starting materials that are both innately reactive and sterically accessible or that are predisposed by a functional group amenable to direct a catalyst. However, selective reactions at unbiased sites of substrates remain challenging and typically require additional pre-activation steps or the use of highly reactive reagents. Herein, we report dual-catalytic transition metal systems that merge a reversible activation cycle with a functionalization cycle, together enabling functionalization of substrates at their inherently unreactive sites. By engaging the Ru- or Fe-catalyzed equilibrium between an alcohol and an aldehyde, Pd-catalyzed <i>b</i>-arylation of aliphatic alcohols and Rh-catalyzed <i>g</i>-hydroarylation of allylic alcohols were developed. The mild conditions, functional group tolerance and broad scope of the methodologies (81 examples) demonstrate the synthetic applicability of the dual-catalytic systems. In a broader context, this work highlights the potential of the multi-catalytic approach to address challenging transformations to circumvent the multi-step procedures and the use of highly reactive reagents in organic synthesis.</b>

scholarly journals Dual-Catalytic Transition Metal Systems for Functionalization of Unreactive Sites of Molecules

2018 ◽  
Author(s):  
Dawid Lichosyt ◽  
Yang Zhang ◽  
Karolina Hurej ◽  
Pawel Dydio
Keyword(s):  
Transition Metal ◽  
Organic Synthesis ◽  
Functional Group ◽  
Aliphatic Alcohols ◽  
Catalytic Reactions ◽  
Allylic Alcohols ◽  
Catalytic Systems ◽  
Mild Conditions ◽  
Broad Scope ◽  
Activation Cycle

<b>Catalytic reactions occur readily at sites of starting materials that are both innately reactive and sterically accessible or that are predisposed by a functional group amenable to direct a catalyst. However, selective reactions at unbiased sites of substrates remain challenging and typically require additional pre-activation steps or the use of highly reactive reagents. Herein, we report dual-catalytic transition metal systems that merge a reversible activation cycle with a functionalization cycle, together enabling functionalization of substrates at their inherently unreactive sites. By engaging the Ru- or Fe-catalyzed equilibrium between an alcohol and an aldehyde, Pd-catalyzed <i>b</i>-arylation of aliphatic alcohols and Rh-catalyzed <i>g</i>-hydroarylation of allylic alcohols were developed. The mild conditions, functional group tolerance and broad scope of the methodologies (81 examples) demonstrate the synthetic applicability of the dual-catalytic systems. In a broader context, this work highlights the potential of the multi-catalytic approach to address challenging transformations to circumvent the multi-step procedures and the use of highly reactive reagents in organic synthesis.</b>

Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

2020 ◽  
Author(s):  
Laurent Sévery ◽  
Jacek Szczerbiński ◽  
Mert Taskin ◽  
Isik Tuncay ◽  
Fernanda Brandalise Nunes ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Heterogeneous Systems ◽  
Catalytic Systems ◽  
New Approach ◽  
Molecular Systems ◽  
Electrode Surfaces ◽  
Catalytic Surfaces ◽  
Oxide Electrodes ◽  
The Stability ◽  
Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

Chiral imidazolidinones: A class of priviliged organocatalysts in stereoselective organic synthesis

2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Laura Raimondi ◽  
Chiara Faverio ◽  
Monica Fiorenza Boselli
Keyword(s):  
Pharmaceutical Industry ◽  
Green Chemistry ◽  
Organic Synthesis ◽  
Catalytic Synthesis ◽  
Biological Chemistry ◽  
Chiral Molecules ◽  
Catalytic Systems ◽  
Drug Synthesis ◽  
Industry Needs

AbstractChiral molecules hold a mail position in Organic and Biological Chemistry, so pharmaceutical industry needs suitable strategies for drug synthesis. Moreover, Green Chemistry procedures are increasingly required in order to avoid environment deterioration. Catalytic synthesis, in particular organocatalysis, in thus a continuously expanding field. A survey of more recent researches involving chiral imidazolidinones is here presented, with a particular focus on immobilized catalytic systems.

Bioresorbable Microspheres as Injectable Cell Carrier: FRom Preparation to in Vitro Evaluation

1998 ◽  
Vol 550 ◽  
Author(s):  
Y. Senuma ◽  
S. Franceschin ◽  
J. G. Hilborn ◽  
P. Tissiéres ◽  
P. Frey
Keyword(s):  
Cultured Cells ◽  
Urothelial Cells ◽  
New Approach ◽  
Muscular Structure ◽  
Cell Carrier ◽  
Support Matrix ◽  
Vesico Ureteral Reflux

AbstractA new approach to the vesico-ureteral reflux could be a local regeneration of the defective vesicoureteral junction by transplanting living cells to the target site. The aim of this work is to provide a long-term effective treatment by producing bioresorbable microspheres which can act as support matrix for those cells, with the goal of an in vivo transfer of the in vitro cultured cells with a minimal surgical procedure. After microsphere degradation, the cells should be integrated into the muscular structure of the junction. Most innovative is that these are cultured muscle and urothelial cells from the bladder of the same patient.

Metalloporphyrin catalysts for organic synthesis

2004 ◽  
Vol 08 (09) ◽  
pp. 1166-1171 ◽  
Author(s):  
Gérard Simonneaux ◽  
Pietro Tagliatesta
Keyword(s):  
Organic Synthesis ◽  
Enantiomeric Excess ◽  
Catalytic Reactions ◽  
Terminal Alkynes ◽  
Asymmetric Oxidation ◽  
Carbene Transfer ◽  
Catalytic Asymmetric ◽  
Chiral Systems ◽  
Metalloporphyrin Catalysts

Novel chiral systems for the catalytic asymmetric oxidation and cyclopropanation of olefins based on metalloporphyrins containing iron, ruthenium and manganese, have been recently introduced. High catalyst turnover numbers and sometimes high enantiomeric excess were observed. New catalytic reactions with metalloporphyrins have recently been reported; these are the olefination of aldehydes and cyclotrimerization of terminal alkynes. Dendrimers and polymers containing metalloporphyrins, have also been found to be efficient catalysts for oxidation and carbene transfer.

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