Enantioselective organocatalytic amination of 2-perfluoroalkyl-oxazol-5(2H)-ones towards synthesis of chiral N,O-aminals with perfluoroalkyl and amino groups

2021 ◽  
Author(s):  
Bo Zhu ◽  
Tianxiao Yang ◽  
Yingxin Gu ◽  
Shuping Zhu ◽  
Gongming Zhu ◽  
...  
Keyword(s):  
Tertiary Amine ◽  
Bifunctional Catalyst ◽  
Amino Groups ◽  
Asymmetric Transformation ◽  
Transformation Processes

Herein, the first highly enantioselective amination at the C-2 position of 2-perfluoroalkyl-oxazol-5(2H)-ones to phenylazocarboxylates using (1R,2R)-cyclohexane-1,2-diamine-derived urea-tertiary amine as a bifunctional catalyst is presented. Two efficient asymmetric transformation processes were...

scholarly journals Enantioselective synthesis of 2,3-disubstituted trans-2,3-dihydrobenzofurans using a Brønsted base/thiourea bifunctional catalyst

2016 ◽  
Vol 14 (30) ◽  
pp. 7268-7274 ◽  
Author(s):  
Diego-Javier Barrios Antúnez ◽  
Mark D. Greenhalgh ◽  
Charlene Fallan ◽  
Alexandra M. Z. Slawin ◽  
Andrew D. Smith
Keyword(s):  
Tertiary Amine ◽  
Michael Addition ◽  
Bifunctional Catalyst ◽  
Enantioselective Synthesis ◽  
Brønsted Base

The enantioselective synthesis of 2,3-disubstituted trans-2,3-dihydrobenzofuran derivatives via intramolecular Michael addition has been developed using a bifunctional tertiary amine–thiourea catalyst.

scholarly journals Expanding the Family of Octahedral Chiral-at-Metal Cobalt(III) Catalysts by Introducing Tertiary Amine Moiety into the Ligand

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 152
Author(s):  
Tat’yana F. Savel’yeva ◽  
Olga V. Khromova ◽  
Vladimir A. Larionov ◽  
Alexander F. Smol’yakov ◽  
Ivan V. Fedyanin ◽  
...  
Keyword(s):  
Molecular Electrostatic Potential ◽  
Bifunctional Catalyst ◽  
Cd Spectroscopy ◽  
Catalyst Design ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
Hydrogen Bond Donor ◽  
Catalytic Potential ◽  
The Family ◽  
Brønsted Base

Chiral metal-templated complexes are attractive catalysts for organic synthetic transformations. Herein, we introduce a novel chiral cobalt(III)-templated complex based on chiral trans-3,4-diamino-1-benzylpyrrolidine and 3,5-di-tert-butyl-salicylaldehyde which features both hydrogen bond donor and Brønsted base functionalities. The obtained complexes were fully characterized by 1H, 13C NMR, IR-, UV-vis, CD-spectroscopy and by a single X-ray diffraction analysis. It was shown that chlorine anion is connected with amino groups of the complex via a hydrogen bonding. DFT calculations of charges and molecular electrostatic potential of the cobalt(III) complex showed that the basicity of the complex is certainly diminished as compared with the routine tertiary amines but the acidity of the conjugated acid of the complex should be increased. Thus, the catalytic potential of the complex may be much greater as a chiral acid than a chiral base. We believe that this work opens a new way in chiral bifunctional catalyst design.

Synthesis and bifunctional catalysis of metal nanoparticle-loaded periodic mesoporous organosilicas modified with amino groups

RSC Advances ◽  
2015 ◽  
Vol 5 (89) ◽  
pp. 72653-72658 ◽  
Author(s):  
Yu Horiuchi ◽  
Dang Do Van ◽  
Yusuke Yonezawa ◽  
Masakazu Saito ◽  
Satoru Dohshi ◽  
...  
Keyword(s):  
Present Article ◽  
Bifunctional Catalyst ◽  
Metal Nanoparticle ◽  
Bifunctional Catalysis ◽  
Amino Groups ◽  
Periodic Mesoporous Organosilica ◽  
Catalytic Activities ◽  
Periodic Mesoporous Organosilicas ◽  
Mesoporous Organosilica ◽  
Mesoporous Organosilicas

The present article describes the development of a periodic mesoporous organosilica (PMO)-based bifunctional catalyst that includes both oxidative and base catalytic activities.

Aldehyde gold clusters for molecular labeling

1995 ◽  
Vol 53 ◽  
pp. 858-859
Author(s):  
James F. Hainfeld ◽  
Frederic R. Furuya
Keyword(s):  
Covalent Bond ◽  
Aldehyde Group ◽  
Gold Clusters ◽  
Side Reactions ◽  
Amino Groups ◽  
Sodium Cyanoborohydride ◽  
Schiff’S Base ◽  
Protein Molecules ◽  
Hydroxysuccinimide Esters ◽  
Primary Amino

Glutaraldehyde is a useful tissue and molecular fixing reagents. The aldehyde moiety reacts mainly with primary amino groups to form a Schiff's base, which is reversible but reasonably stable at pH 7; a stable covalent bond may be formed by reduction with, e.g., sodium cyanoborohydride (Fig. 1). The bifunctional glutaraldehyde, (CHO-(CH2)3-CHO), successfully stabilizes protein molecules due to generally plentiful amines on their surface; bovine serum albumin has 60; 59 lysines + 1 α-amino. With some enzymes, catalytic activity after fixing is preserved; with respect to antigens, glutaraldehyde treatment can compromise their recognition by antibodies in some cases. Complicating the chemistry somewhat are the reported side reactions, where glutaraldehyde reacts with other amino acid side chains, cysteine, histidine, and tyrosine. It has also been reported that glutaraldehyde can polymerize in aqueous solution. Newer crosslinkers have been found that are more specific for the amino group, such as the N-hydroxysuccinimide esters, and are commonly preferred for forming conjugates. However, most of these linkers hydrolyze in solution, so that the activity is lost over several hours, whereas the aldehyde group is stable in solution, and may have an advantage of overall efficiency.

The Action of Thrombin on Modified Fibrinogen

1983 ◽  
Vol 49 (03) ◽  
pp. 208-213
Author(s):  
A J Osbahr
Keyword(s):  
Physical Properties ◽  
Negative Charge ◽  
Lysine Residue ◽  
Fibrinopeptide A ◽  
Amino Groups ◽  
Lysine Residues ◽  
Citraconic Anhydride

SummaryThe modification of canine fibrinogen with citraconic anhydride modified the ε-amino groups of the fibrinogen and at the same time generated additional negative charges into the protein. The addition of thrombin to the modified fibrinogen did not induce polymerization; however, the fibrinopeptide was released at a faster rate than from the unmodified fibrinogen. The physical properties of the citraconylated fibrinogen were markedly altered by the modification of 50-60 lysine residues in one hour. A modified fibrinopeptide-A was released by thrombin from the modified fibrinogen and was electrophoretically more anionic than the unmodified fibrinopeptide-A. Edman analysis confirmed the modification of the lysine residue present in the peptide. The rate of removal of citraconylated fibrinopeptide-A from modified fibrinogen by thrombin was 30 to 40 percent greater than the cleavage of unmodified fibrinopeptide-A from unmodified fibrinogen. However, the modification of 60 or more lysine residues in the fibrinogen produced a decrease in the rate of cleavage of citraconylated fibrinopeptide-A. The results suggest that additional negative charge in the vicinity of the attachment of fibrinopeptide-A to canine fibrinogen aids in the removal of the peptide by thrombin.

COMPARATIVE STUDIES OF THE POTENTIATION OF CORTICOTROPHIN ACTIVITY BY SEVERAL INACTIVE DERIVATIVES

1963 ◽  
Vol 42 (2) ◽  
pp. 209-213 ◽  
Author(s):  
Arthur I. Cohen ◽  
Edward H. Frieden
Keyword(s):  
Biological Activity ◽  
Comparative Studies ◽  
Free Amino ◽  
Hormonal Activity ◽  
Amino Groups

ABSTRACT A number of corticotrophin analogues have been prepared, some of which potentiate the biological activity of the untreated hormone in vitro. The free amino groups of corticotrophin appear to be essential not only for hormonal activity, but also for the interaction of the analogues with the tissue corticotrophin inactivating system which is assumed to account for the potentiating effect.

THE IMPACT OF UKRAINE'S EXCISE DUTY POLICY ON THE TRANSFORMATION PROCESSES OF THE TOBACCO MARKET

2020 ◽  
Vol 2020 (10) ◽  
pp. 19-33
Author(s):  
Nadiia NOVYTSKA ◽  
◽  
Inna KHLIEBNIKOVA ◽  
Keyword(s):  
Structural Changes ◽  
Tax Avoidance ◽  
Transformation Process ◽  
State Regulation ◽  
Tobacco Products ◽  
Excise Duty ◽  
Increasing Demand ◽  
High Level ◽  
The Impact ◽  
Transformation Processes

The market of tobacco products in Ukraine is one of the most dynamic and competitive. It develops under the influence of certain factors that cause structural changes, therefore, the aim of the article is to conduct a comprehensive analysis of transformation processes in the market of tobacco and their alternatives in Ukraine and identify the factors that cause them. The high level of tax burden and the proliferation of alternative products with a potentially lower risk to human health, including heating tobacco products and e-cigarettes, are key factors in the market’s transformation process. Their presence leads to an increase in illicit turnover of tobacco products, which accounts for 6.37% of the market, and the gradual replacement of cigarettes with alternative products, which account for 12.95%. The presence on the market of products that are not taxed or taxed at lower rates is one of the reasons for the reduction of excise duty revenues. According to the results of 2019, the planned indicators of revenues were not met by 23.5%. Other reasons for non-fulfillment of excise duty revenues include: declining dynamics of the tobacco products market; reduction in the number of smokers; reorientation of «cheap whites» cigarette flows from Ukraine to neighboring countries; tax avoidance. Prospects for further research are identified, namely the need to develop measures for state regulation and optimization of excise duty taxation of tobacco products and their alternatives, taking into account the risks to public health and increasing demand of illegal products.

TLC/HPTLC and HPLC methods for monitoring microbial transformation processes

2004 ◽  
Vol 17 (2) ◽  
pp. 132-136 ◽  
Author(s):  
Balázs Erdélyi ◽  
Antal Szabó ◽  
László Birincsik ◽  
Gábor Seres ◽  
János Salát ◽  
...  
Keyword(s):  
Microbial Transformation ◽  
Transformation Processes
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