scholarly journals Light-driven carbon−carbon bond formation via CO2reduction catalyzed by complexes of CdS nanorods and a 2-oxoacid oxidoreductase

2019 ◽  
Vol 117 (1) ◽  
pp. 135-140 ◽  
Author(s):  
Hayden Hamby ◽  
Bin Li ◽  
Katherine E. Shinopoulos ◽  
Helena R. Keller ◽  
Sean J. Elliott ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Enzyme Catalysis ◽  
Transient Absorption ◽  
Tricarboxylic Acid Cycle ◽  
Semiconductor Nanocrystals ◽  
Bond Formation ◽  
Critical Role ◽  
Transient Absorption Spectroscopy ◽  
Carbon Bond ◽  
Carbon Carbon Bond

Redox enzymes are capable of catalyzing a vast array of useful reactions, but they require redox partners that donate or accept electrons. Semiconductor nanocrystals provide a mechanism to convert absorbed photon energy into redox equivalents for enzyme catalysis. Here, we describe a system for photochemical carbon−carbon bond formation to make 2-oxoglutarate by coupling CO2with a succinyl group. Photoexcited electrons from cadmium sulfide nanorods (CdS NRs) transfer to 2-oxoglutarate:ferredoxin oxidoreductase fromMagnetococcus marinusMC-1 (MmOGOR), which catalyzes a carbon−carbon bond formation reaction. We thereby decouple MmOGOR from its native role in the reductive tricarboxylic acid cycle and drive it directly with light. We examine the dependence of 2-oxoglutarate formation on a variety of factors and, using ultrafast transient absorption spectroscopy, elucidate the critical role of electron transfer (ET) from CdS NRs to MmOGOR. We find that the efficiency of this ET depends strongly on whether the succinyl CoA (SCoA) cosubstrate is bound at the MmOGOR active site. We hypothesize that the conformational changes due to SCoA binding impact the CdS NR−MmOGOR interaction in a manner that decreases ET efficiency compared to the enzyme with no cosubstrate bound. Our work reveals structural considerations for the nano−bio interfaces involved in light-driven enzyme catalysis and points to the competing factors of enzyme catalysis and ET efficiency that may arise when complex enzyme reactions are driven by artificial light absorbers.

scholarly journals Crystal structure of cytoplasmic acetoacetyl-CoA thiolase fromSaccharomyces cerevisiae

2018 ◽  
Vol 74 (1) ◽  
pp. 6-13 ◽  
Author(s):  
Pengfei Zhou ◽  
Zhongliang Zhu ◽  
Muhammad Hidayatullah Khan ◽  
Peiyi Zheng ◽  
Maikun Teng ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Mevalonate Pathway ◽  
Condensation Reaction ◽  
Bond Formation ◽  
Binding Pocket ◽  
Binding Mode ◽  
Carbon Bond ◽  
Carbon Carbon Bond ◽  
Binding Cavity ◽  
Comparative Binding

Thiolases are vital enzymes which participate in both degradative and biosynthetic pathways. Biosynthetic thiolases catalyze carbon–carbon bond formation by a Claisen condensation reaction. The cytoplasmic acetoacetyl-CoA thiolase fromSaccharomyces cerevisiae, ERG10, catalyses carbon–carbon bond formation in the mevalonate pathway. The structure of aS. cerevisiaebiosynthetic thiolase has not previously been reported. Here, crystal structures of apo ERG10 and its Cys91Ala variant were solved at resolutions of 2.2 and 1.95 Å, respectively. The structure determined shows that ERG10 shares the characteristic thiolase superfamily fold, with a similar active-site architecture to those of type II thiolases and a similar binding pocket, apart from Ala159 at the entrance to the pantetheine-binding cavity, which appears to be a determinant of the poor binding ability of the substrate. Moreover, comparative binding-pocket analysis of moleculeBin the asymmetric unit of the apo structure with that of the CoA-bound complex of human mitochondrial acetoacetyl-CoA thiolase indicates the canonical binding mode of CoA. Furthermore, the steric hindrance revealed in a structural comparison of moleculeAwith the CoA-bound form raise the possibility of conformational changes that are associated with substrate binding.

Carbon Dioxide-Mediated C(sp2)–H Arylation of Primary and Secondary Benzylamines

2018 ◽  
Author(s):  
Mohit Kapoor ◽  
Pratibha Chand-Thakuri ◽  
Michael Young
Keyword(s):  
Carbon Dioxide ◽  
Transition Metal ◽  
Bond Activation ◽  
Bond Formation ◽  
Carbon Bond ◽  
Chelate Effect ◽  
Free Amine ◽  
Carbon Carbon Bond ◽  
New Strategy ◽  
Metal Catalyzed

Carbon-carbon bond formation by transition metal-catalyzed C–H activation has become an important strategy to fabricate new bonds in a rapid fashion. Despite the pharmacological importance of <i>ortho</i>-arylbenzylamines, however, effective <i>ortho</i>-C–C bond formation from C–H bond activation of free primary and secondary benzylamines using Pd<sup>II</sup> remains an outstanding challenge. Presented herein is a new strategy for constructing <i>ortho</i>-arylated primary and secondary benzylamines mediated by carbon dioxide (CO<sub>2</sub>). The use of CO<sub>2</sub> is critical to allowing this transformation to proceed under milder conditions than previously reported, and that are necessary to furnish free amine products that can be directly used or elaborated without the need for deprotection. In cases where diarylation is possible, a chelate effect is demonstrated to facilitate selective monoarylation.

Modern Organic Synthesis in the Laboratory

2008 ◽  
Author(s):  
Jie Jack Li ◽  
Chris Limberakis ◽  
Derek A. Pflum
Keyword(s):  
Organic Chemistry ◽  
Graduate Students ◽  
Organic Synthesis ◽  
Functional Group ◽  
Bond Formation ◽  
Reaction Conditions ◽  
Carbon Bond ◽  
Oxidation Reduction ◽  
Carbon Carbon Bond ◽  
Daunting Task

Searching for reaction in organic synthesis has been made much easier in the current age of computer databases. However, the dilemma now is which procedure one selects among the ocean of choices. Especially for novices in the laboratory, it becomes a daunting task to decide what reaction conditions to experiment with first in order to have the best chance of success. This collection intends to serve as an "older and wiser lab-mate" one could have by compiling many of the most commonly used experimental procedures in organic synthesis. With chapters that cover such topics as functional group manipulations, oxidation, reduction, and carbon-carbon bond formation, Modern Organic Synthesis in the Laboratory will be useful for both graduate students and professors in organic chemistry and medicinal chemists in the pharmaceutical and agrochemical industries.

scholarly journals Transition Metal-Catalyzed α-Position Carbon–Carbon Bond Formations of Carbonyl Derivatives

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 861 ◽  
Author(s):  
Ha-Eun Lee ◽  
Dopil Kim ◽  
Ahrom You ◽  
Myung Hwan Park ◽  
Min Kim ◽  
...  
Keyword(s):  
Transition Metal ◽  
Carbonyl Compounds ◽  
Bond Formation ◽  
Chiral Ligand ◽  
Catalytic Systems ◽  
Carbon Bond ◽  
Carbonyl Derivatives ◽  
Carbon Carbon Bond ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

α-Functionalization of carbonyl compounds in organic synthesis has traditionally been accomplished via classical enolate chemistry. As α-functionalized carbonyl moieties are ubiquitous in biologically and pharmaceutically valuable molecules, catalytic α-alkylations have been extensively studied, yielding a plethora of practical and efficient methodologies. Moreover, stereoselective carbon–carbon bond formation at the α-position of achiral carbonyl compounds has been achieved by using various transition metal–chiral ligand complexes. This review describes recent advances—in the last 20 years and especially focusing on the last 10 years—in transition metal-catalyzed α-alkylations of carbonyl compounds, such as aldehydes, ketones, imines, esters, and amides and in efficient carbon–carbon bond formations. Active catalytic species and ligand design are discussed, and mechanistic insights are presented. In addition, recently developed photo-redox catalytic systems for α-alkylations are described as a versatile synthetic tool for the synthesis of chiral carbonyl-bearing molecules.

scholarly journals Synthesis and Properties of the Fluoroalkylated Oligomers with Carbon-Carbon Bond Formation

1992 ◽  
Vol 41 (8) ◽  
pp. 649-657 ◽  
Author(s):  
Hideo SAWADA ◽  
Yoshihiro MINOSHIMA ◽  
Yue-Fa GONG ◽  
Takeo MATSUMOTO ◽  
Masanori KOSUGI ◽  
...  
Keyword(s):  
Bond Formation ◽  
Carbon Bond ◽  
Carbon Carbon Bond
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