Recent advances in reactions promoted by amino acids and oligopeptides

2020 ◽  
Vol 5 (11) ◽  
Author(s):  
Ierasia Triandafillidi ◽  
Errika Voutyritsa ◽  
Christoforos G. Kokotos
Keyword(s):  
Amino Acids ◽  
Reaction Mechanisms ◽  
Aldol Reactions ◽  
Reaction Conditions ◽  
Michael Reactions ◽  
Recent Advances

AbstractDuring the last 20 years, Organocatalysis has become one of the major fields of Catalysis. Herein, we provide a recent overview on reactions where the use of amino acids and peptides as the organocatalysts was employed. All aspects regarding aldol reactions, Michael reactions, epoxidation, Henry reactions and many others that are crucial for the reaction conditions and reaction mechanisms are discussed.

Recent Advances on Synthesis of 1,4-Benzoxazines and its Derivatives

2021 ◽  
Vol 25 ◽  
Author(s):  
Wei Liang ◽  
Li-Jing Min ◽  
Liang Han ◽  
Xing-Hai Liu
Keyword(s):  
Reaction Mechanisms ◽  
Heterocyclic Compounds ◽  
Synthesis Methods ◽  
Important Class ◽  
Efficient Synthesis ◽  
Reaction Conditions ◽  
Active Structure ◽  
Recent Advances ◽  
The Future

: 1,4-benzoxazine compounds are an important class of heterocyclic compounds. Ever since 1,4-benzoxazine was discovered in 1959, it has attracted chemists due to its unique physiological activities, and their synthesis and application have been studied. However, the traditional synthesis methods of 1,4-benzoxazines have some drawbacks, such as complicated steps, harsh reaction conditions and low yield. Therefore, it is still a significant direction to develop new and efficient synthesis methods. In this paper, the synthesis methods and reaction mechanisms of these compounds are reviewed, and the application prospect of 1,4- benzoxazine and its derivatives as a dominant active structure in the future is discussed.

scholarly journals Design of Iridium N-Heterocyclic Carbene Amino Acid Catalysts for Asymmetric Transfer Hydrogenation of Aryl Ketones

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 671
Author(s):  
Chad M. Bernier ◽  
Joseph S. Merola
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Enantiomeric Excess ◽  
Transfer Hydrogenation ◽  
Acid Catalysts ◽  
Asymmetric Transfer Hydrogenation ◽  
Reaction Conditions ◽  
Chiral Complexes ◽  
Acetophenone Derivatives ◽  
Aryl Ketones

A series of chiral complexes of the form Ir(NHC)2(aa)(H)(X) (NHC = N-heterocyclic carbene, aa = chelated amino acid, X = halide) was synthesized by oxidative addition of -amino acids to iridium(I) bis-NHC compounds and screened for asymmetric transfer hydrogenation of ketones. Following optimization of the reaction conditions, NHC, and amino acid ligands, high enantioselectivity was achieved when employing the Ir(IMe)2(l-Pro)(H)(I) catalyst (IMe = 1,3-dimethylimidazol-2-ylidene), which asymmetrically reduces a range of acetophenone derivatives in up to 95% enantiomeric excess.

Ligand-Driven Advances in Iridium Catalyzed sp3 C-H Borylation: 2,2’-Dipyridylarylmethane

Synlett ◽  
2020 ◽  
Author(s):  
Margaret R Jones ◽  
Nathan D. Schley
Keyword(s):  
Recent Work ◽  
Organic Synthesis ◽  
Functional Group ◽  
Reaction Conditions ◽  
Recent Advances ◽  
Additional Ligand ◽  
Limited Application ◽  
Hydrocarbon Substrates ◽  
Phenanthroline Ligands

The field of catalytic C-H borylation has grown considerably since its founding, providing a means for the preparation of synthetically versatile organoborane products. While sp2 C-H borylation methods have found widespread and practical use in organic synthesis, the analogous sp3 C-H borylation reaction remains challenging and has seen limited application. Existing catalysts are often hindered by incomplete consumption of the diboron reagent, poor functional group tolerance, harsh reaction conditions, and the need for excess or neat substrate. These challenges acutely affect C-H borylation chemistry of unactivated hydrocarbon substrates, which has lagged in comparison to methods for the C-H borylation of activated compounds. Herein we discuss recent advances in sp3 C-H borylation of undirected substrates in the context of two particular challenges: (1) utilization of the diboron reagent and (2) the need for excess or neat substrate. Our recent work on the application of dipyridylarylmethane ligands in sp3 C-H borylation has allowed us to make contributions in this space and has presented an additional ligand scaffold to supplement traditional phenanthroline ligands.

scholarly journals Recent advances in understanding oxygen evolution reaction mechanisms over iridium oxide

2021 ◽  
Author(s):  
Takahiro Naito ◽  
Tatsuya Shinagawa ◽  
Takeshi Nishimoto ◽  
Kazuhiro Takanabe
Keyword(s):  
Reaction Mechanism ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Reaction Mechanisms ◽  
State Of The Art ◽  
Iridium Oxide ◽  
The State ◽  
Computational Studies ◽  
Recent Advances ◽  
Iridium Oxides

Recent spectroscopic and computational studies concerning the oxygen evolution reaction over iridium oxides are reviewed to provide the state-of-the-art understanding of its reaction mechanism.

scholarly journals Recent Advances in Rapid Synthesis of Non-proteinogenic Amino Acids from Proteinogenic Amino Acids Derivatives via Direct Photo-Mediated C–H Functionalization

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5270
Author(s):  
Zhenbo Yuan ◽  
Xuanzhong Liu ◽  
Changmei Liu ◽  
Yan Zhang ◽  
Yijian Rao
Keyword(s):  
Amino Acids ◽  
Direct Synthesis ◽  
Environmentally Friendly ◽  
Powerful Method ◽  
Rapid Synthesis ◽  
Conservation Of Energy ◽  
Mild Conditions ◽  
Recent Advances ◽  
Recent Developments

Non-proteinogenic amino acids have attracted tremendous interest for their essential applications in the realm of biology and chemistry. Recently, rising C–H functionalization has been considered an alternative powerful method for the direct synthesis of non-proteinogenic amino acids. Meanwhile, photochemistry has become popular for its predominant advantages of mild conditions and conservation of energy. Therefore, C–H functionalization and photochemistry have been merged to synthesize diverse non-proteinogenic amino acids in a mild and environmentally friendly way. In this review, the recent developments in the photo-mediated C–H functionalization of proteinogenic amino acids derivatives for the rapid synthesis of versatile non-proteinogenic amino acids are presented. Moreover, postulated mechanisms are also described wherever needed.

scholarly journals A New Route to Non-Natural Aryl-Containing Amino Acids and Their Precursors from Thiophenes

2003 ◽  
Vol 2003 (9) ◽  
pp. 527-528 ◽  
Author(s):  
Krishna Gopal Dongol ◽  
Shuntaro Mataka ◽  
Thies Thiemann
Keyword(s):  
Amino Acids ◽  
Reaction Conditions

Thiophenes may be converted to substituted arenes by oxidative cycloaddition to alkynes or by oxidative cycloaddition to alkenes with subsequent oxidative SO-extrusion. Cyano- and acetylamino-groups do not interfere in the reaction and are stable under the reaction conditions. This transformation can be used as a novel route to non-natural aryl-containing amino acids.

Recent Advances in the Pharmacology of Excitatory Amino Acids in the Mammalian Central Nervous System

Excitotoxins ◽  
1983 ◽  
pp. 43-54 ◽  
Author(s):  
J. Davies ◽  
R. H. Evans ◽  
A. W. Jones ◽  
K. N. Mewett ◽  
D. A. S. Smith ◽  
...  
Keyword(s):  
Amino Acids ◽  
Central Nervous System ◽  
Nervous System ◽  
Excitatory Amino Acids ◽  
Mammalian Central Nervous System ◽  
Recent Advances

scholarly journals Synthesis of new Cα-tetrasubstituted α-amino acids

2009 ◽  
Vol 5 ◽  
Author(s):  
Andreas A Grauer ◽  
Burkhard König
Keyword(s):  
Amino Acids ◽  
Secondary Structure ◽  
Aromatic Aldehydes ◽  
Building Blocks ◽  
Reaction Conditions ◽  
Peptide Backbone ◽  
Aliphatic Aldehydes ◽  
New Class ◽  
Cyclic Amino Acids

Cα-Tetrasubstituted α-amino acids are important building blocks for the synthesis of peptidemimetics with stabilized secondary structure, because of their ability to rigidify the peptide backbone. Recently our group reported a new class of cyclic Cα-tetrasubstituted tetrahydrofuran α-amino acids prepared from methionine and aromatic aldehydes. We now report the extension of this methodology to aliphatic aldehydes. Although such aldehydes are prone to give aldol products under the reaction conditions used, we were able to obtain the target cyclic amino acids in low to moderate yields and in some cases with good diastereoselectivity.

scholarly journals Isolation of Free Amino Acids via Enzymatic Hydrolysis of Tobacco-Derived F1 Protein

2018 ◽  
Vol 28 (4) ◽  
pp. 179-190
Author(s):  
Mehdi Ashraf-Khorassani ◽  
William M. Coleman ◽  
Michael F. Dube ◽  
Larry T. Taylor
Keyword(s):  
Amino Acids ◽  
Enzymatic Hydrolysis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Protein Concentration ◽  
Enzyme Concentration ◽  
Enzymatic Conversion ◽  
Reaction Conditions ◽  
Analytical Methodology ◽  
Hydrolysis Of

SummaryFree amino acids have been isolated via optimized enzymatic hydrolysis of F1 tobacco protein using two cationic resins (Amberlite IR120 and Dowex MAC-2). Optimized enzymatic conversions of the protein as a result of systematic variations in conditions (e.g., time, temperature, pH, enzyme type, enzyme concentration, anaerobic/aerobic environments, and protein concentration) employing commercially available enzymes, were consistently higher than 50% with qualitative amino acid arrays that were consistent with the known composition of tobacco F1 protein. Amberlite IR120 was shown to have a much higher efficiency and capacity for isolation of amino acids from standard solutions and from hydrolysate when compared with the results using Dowex MAC-2. Two columns packed with conditioned Amberlite IR120 (120 × 10 mm,12–15 g resin) and (200 × 25.4 mm, 60–65 g resin) were used to isolate two batches (2.5–3.0 mg and 13–15 mg) of free amino acids, respectively. A relatively inexpensive analytical methodology was developed for rapid analysis of the free amino acids contained within the enzyme hydrolysate. Commercially available enzymes, when employed in optimized reaction conditions, are very effective for enzymatic conversion of tobacco F1 protein to free amino acids.

Peroxovanadates and Its Bio-Mimicking Relation with Vanadium Haloperoxidases

2016 ◽  
pp. 197-219
Author(s):  
Pranjal Saikia ◽  
Saitanya Kumar Bharadwaj ◽  
Abu Taleb Miah
Keyword(s):  
Amino Acids ◽  
Active Site ◽  
High Efficiency ◽  
Recombinant Enzymes ◽  
Vanadium Compounds ◽  
Reaction Conditions ◽  
The Cost ◽  
Major Emphasis ◽  
Protein Active Site

Vanadium Haloperoxidases (VHPOs) have been used in a variety of biotransformations showing remarkable stereoselectivity and regiospecificity. The high efficiency of the enzyme is influenced by the protein active site and the role of certain amino acids in activation of vanadium(V)-bound peroxide for halide oxidation. The use of natural or recombinant enzymes, or biomimetic vanadium compounds brings up issues regarding the cost of production and reaction conditions. In this chapter, the primary intent is to provide a simple and clear picture of functional mimicking nature of peroxovanadium compounds with haloperoxidases enzymes to the readers. Major emphasis would be given to examine the reactivity of the vanadium haloperoxidases with mechanism.

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