β-Keto Acids in Asymmetric Metal catalysis and Organocatalysis

2021 ◽  
Author(s):  
Wei Qin ◽  
Mahboob Subhani ◽  
Chunhui Jiang ◽  
Hongfei Lu
Keyword(s):  
Organic Synthesis ◽  
Keto Acid ◽  
Metal Catalysis ◽  
Keto Acids

The β-keto acid, an ideal surrogate of inactive ketones, plays an important role in organic synthesis. The asymmetric decarboxylative reaction by using β-ketoacids is one which is being studied the...

An electrochemical perspective on the roles of ligands in the merger of transition-metal catalysis and electrochemistry

2020 ◽  
Author(s):  
Ke-Yin Ye ◽  
Jun-Song Zhong ◽  
Yi Yu ◽  
Zhaojiang Shi
Keyword(s):  
Transition Metal ◽  
Organic Synthesis ◽  
Transition Metal Catalysis ◽  
Metal Catalysis

The merger of transition-metal catalysis and electrochemistry has been emerging as a very versatile and robust synthetic tool in organic synthesis. Like in their non-electrochemical variants, ligands also play crucial...

Transition metal catalysis in organic synthesis: reflections, chirality and new vistas

1999 ◽  
Vol 71 (8) ◽  
pp. 1425-1433 ◽  
Author(s):  
Pavel Kočovský ◽  
Andrei V. Malkov ◽  
Štěpán Vyskočil ◽  
Guy C. Lloyd-Jones
Keyword(s):  
Transition Metal ◽  
Organic Synthesis ◽  
Transition Metal Catalysis ◽  
Metal Catalysis

scholarly journals Convenient Genetic Encoding of Phenylalanine Derivatives through Their α-Keto Acid Precursors

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1358
Author(s):  
Li Liu ◽  
Bohao Wang ◽  
Sheng Li ◽  
Fengyuan Xu ◽  
Qi He ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Genetic Code ◽  
Fluorescent Proteins ◽  
Coli Strain ◽  
Keto Acid ◽  
Phenylpyruvic Acid ◽  
Genetic Encoding ◽  
Keto Acids ◽  
Genetic Code Expansion ◽  
And Function

The activity and function of proteins can be improved by incorporation of non-canonical amino acids (ncAAs). To avoid the tedious synthesis of a large number of chiral phenylalanine derivatives, we synthesized the corresponding phenylpyruvic acid precursors. Escherichia coli strain DH10B and strain C321.ΔA.expΔPBAD were selected as hosts for phenylpyruvic acid bioconversion and genetic code expansion using the MmPylRS/pyltRNACUA system. The concentrations of keto acids, PLP and amino donors were optimized in the process. Eight keto acids that can be biotransformed and their coupled genetic code expansions were identified. Finally, the genetic encoded ncAAs were tested for incorporation into fluorescent proteins with keto acids.

scholarly journals Sulfoxonium Ylide Derived Metal Carbenoids in Organic Synthesis

Synthesis ◽  
2018 ◽  
Vol 51 (03) ◽  
pp. 612-628 ◽  
Author(s):  
Janakiram Vaitla ◽  
Annette Bayer
Keyword(s):  
Transition Metal ◽  
Organic Synthesis ◽  
Transition Metal Catalysis ◽  
Transfer Reactions ◽  
Reaction Conditions ◽  
Widespread Application ◽  
Metal Catalysis ◽  
Half Century ◽  
Metal Carbenoids

As pioneered by Corey and Chaykovsky, sulfoxonium ylides have had widespread application in organic synthesis for more than a half century. In most of the reactions, sulfoxonium ylides were used to react with electrophiles. Under suitable reaction conditions these ylides can generate metal carbenoids and react with nucleophiles. By combining the typical reactivity of sulfoxonium ylides with transition-metal catalysis, a growing number of investigations have expanded their application in organic synthesis. This review provides an update on the preparation of sulfoxonium ylides and their applications in carbenoid transfer reactions.1 Introduction2 Preparation of Sulfoxonium Ylides3 Investigation for Carbenoid Formation from Sulfoxonium Ylide 4 X–H (X = N, O, S, C) Functionalization Reactions5 Polymerizaton of Carbenoids Generated from Sulfoxonium Ylides6 Conclusion and Perspective

Transport of alpha-keto analogues of amino acids across blood-brain barrier in rats

1982 ◽  
Vol 243 (4) ◽  
pp. E272-E277
Author(s):  
A. R. Conn ◽  
R. D. Steele
Keyword(s):  
Blood Brain Barrier ◽  
Transport System ◽  
Ketone Bodies ◽  
Brain Barrier ◽  
Sodium Pentobarbital ◽  
Keto Acid ◽  
Dual Isotope ◽  
Common System ◽  
Blood Brain ◽  
Keto Acids

The transport of 14C-labeled alpha-keto acids across the blood-brain barrier (BBB) was studied in rats anesthetized with sodium pentobarbital using a modification of a single-injection dual-isotope technique. alpha-Keto acids were found to cross the BBB via a saturable carrier-mediated transport system that may be specific based on lack of inhibition by glucose, isoleucine, and ketone bodies on the uptake of tracer levels of 14C-labeled alpha-keto acids. alpha-Ketobutyrate and alpha-keto-gamma-methiolbutyrate, both straight chain keto acids, and alpha-ketoisocaproate, a branched-chain keto acid, appeared to cross the barrier by a common carrier based on cross-inhibition studies. Aromatic keto acids had no effect on the uptake of tracer levels of these 14C-keto acids. The Km of transport of alpha-ketobutyrate, alpha-ketoisocaproate, and alpha-keto-gamma-methiolbutyrate, was 0.11, 0.60, and 0.33 mM, respectively. The corresponding Vmax was 15.7, 73.3, and 30.2 nmol . g-1 . min-1. Phenylpyruvate was found not to cross the BBB. Inhibition of brain uptake of alpha-keto acids by propionate and pyruvate, and not by DL-beta-hydroxybutyrate suggests that alpha-keto acids and monocarboxylic acids are transported either via a common system independent of ketone bodies or share an affinity with a monocarboxylic acid and an alpha-keto acid transport system.

Transamination of branched-chain keto acids by isolated perfused rat kidney.

1978 ◽  
Vol 235 (1) ◽  
pp. E47
Author(s):  
W E Mitch ◽  
W Chan
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Branched Chain Amino Acid ◽  
Keto Acids ◽  
Perfused Rat Kidney ◽  
Branched Chain ◽  
Branched Chain Keto Acids ◽  
Isolated Rat

Isolated rat kidney perfused without substrate released serine, glycine, and taurine, and substantially smaller amounts of other amino acids. When branched-chain keto acids were added, the corresponding amino acids were released at rates amounting to 15-25% of keto acid disappearance. Perfusion with 2 mM alpha-keto-isovalerate or alpha-keto-beta-methylvalerate caused an increased glucose release amounting to 18-23% of keto acid disappearance. The activity of branched-chain amino acid transferase (BATase) was significantly stimulated by perfusion with the analogue of leucine, but not by perfusion with alpha-ketoglutarate, the analogues of valine or isoleucine, or with leucine itself. These findings document that the kidney converts branched-chain keto acids in part to the corresponding amino acids and suggest that the keto analogue of leucine may be involved in the control of renal BATase activity, thereby indirectly regulating the metabolism of branched-chain amino acids.

scholarly journals Accumulation of α-Keto Acids as Essential Components in Cyanide Assimilation by Pseudomonas fluorescens NCIMB 11764

1998 ◽  
Vol 64 (11) ◽  
pp. 4452-4459 ◽  
Author(s):  
Daniel A. Kunz ◽  
Jui-Lin Chen ◽  
Guangliang Pan
Keyword(s):  
Pseudomonas Fluorescens ◽  
Culture Fluid ◽  
Maximal Activity ◽  
Resonance Spectroscopy ◽  
Keto Acid ◽  
Growth Substrate ◽  
Reaction Products ◽  
Cell Extracts ◽  
Keto Acids ◽  
Essential Components

ABSTRACT Pyruvate (Pyr) and α-ketoglutarate (αKg) accumulated when cells of Pseudomonas fluorescens NCIMB 11764 were cultivated on growth-limiting amounts of ammonia or cyanide and were shown to be responsible for the nonenzymatic removal of cyanide from culture fluids as previously reported (J.-L. Chen and D. A. Kunz, FEMS Microbiol. Lett. 156:61–67, 1997). The accumulation of keto acids in the medium paralleled the increase in cyanide-removing activity, with maximal activity (760 μmol of cyanide removed min−1 ml of culture fluid−1) being recovered after 72 h of cultivation, at which time the keto acid concentration was 23 mM. The reaction products that formed between the biologically formed keto acids and cyanide were unambiguously identified as the corresponding cyanohydrins by 13C nuclear magnetic resonance spectroscopy. Both the Pyr and α-Kg cyanohydrins were further metabolized by cell extracts and served also as nitrogenous growth substrates. Radiotracer experiments showed that CO2 (and NH3) were formed as enzymatic conversion products, with the keto acid being regenerated as a coproduct. Evidence that the enzyme responsible for cyanohydrin conversion is cyanide oxygenase, which was shown previously to be required for cyanide utilization, is based on results showing that (i) conversion occurred only when extracts were induced for the enzyme, (ii) conversion was oxygen and reduced-pyridine nucleotide dependent, and (iii) a mutant strain defective in the enzyme was unable to grow when it was provided with the cyanohydrins as a growth substrate. Pyr and αKg were further shown to protect cells from cyanide poisoning, and excretion of the two was directly linked to utilization of cyanide as a growth substrate. The results provide the basis for a new mechanism of cyanide detoxification and assimilation in which keto acids play an essential role.

scholarly journals Vinylogous and Arylogous Stereoselective Base-Promoted Phase-Transfer Catalysis

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1545
Author(s):  
Assunta D’Amato ◽  
Giorgio Della Sala
Keyword(s):  
Organic Synthesis ◽  
Phase Transfer Catalysis ◽  
Negative Charge ◽  
Phase Transfer ◽  
Bond Formation ◽  
Metal Catalysis ◽  
Carbon Nucleophiles ◽  
Unsaturated Compounds

Vinylogous enolate and enolate-type carbanions, generated by deprotonation of α,β-unsaturated compounds and characterized by delocalization of the negative charge over two or more carbon atoms, are extensively used in organic synthesis, enabling functionalization and C–C bond formation at remote positions. Similarly, reactions with electrophiles at benzylic and heterobenzylic position are performed through generation of arylogous and heteroarylogous enolate-type nucleophiles. Although widely exploited in metal-catalysis and organocatalysis, it is only in recent years that the vinylogy and arylogy principles have been translated fruitfully in phase-transfer catalyzed processes. This review provides an overview of the methods developed to date, involving vinylogous and (hetero)arylogous carbon nucleophiles under phase-transfer catalytic conditions, highlighting main mechanistic aspects.

Metal Catalysis with Microwaves in Organic Synthesis: a Personal Account

2020 ◽  
Vol 2020 (29) ◽  
pp. 4435-4446 ◽  
Author(s):  
Elena Petricci ◽  
Elena Cini ◽  
Maurizio Taddei
Keyword(s):  
Organic Synthesis ◽  
Personal Account ◽  
Metal Catalysis
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