Sequential Addition of Amines to Nitrile and Carbon–Carbon Multiple Bond: A Route to 7-Amino-5H-dibenzo[c,e]azepines

2021 ◽  
Vol 23 (17) ◽  
pp. 6946-6950
Author(s):  
Kun Hu ◽  
Ruiting Liu ◽  
Xigeng Zhou
Keyword(s):  
Multiple Bond ◽  
Sequential Addition

The Inhibition of Platelet Aggregation by an Aorta Intima Extract

1974 ◽  
Vol 32 (02/03) ◽  
pp. 417-431 ◽  
Author(s):  
A. du P Heyns ◽  
D. J van den Berg ◽  
G. M Potgieter ◽  
F. P Retief
Keyword(s):  
Platelet Aggregation ◽  
Degradation Products ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Protective Role ◽  
Vascular Trauma ◽  
Wear And Tear ◽  
Sequential Addition ◽  
Aggregation Activity

SummaryThe platelet aggregating activity of extracts of different layers of the arterial wall was compared to that of Achilles tendon. Arterial media and tendon extracts, adjusted to equivalent protein content as an index of concentration, aggregated platelets to the same extent but an arterial intima extract did not aggregate platelets. Platelet aggregation induced by collagen could be inhibited by mixing with intima extract, but only to a maximum of about 80%. Pre-mixing adenosine diphosphate (ADP) with intima extracts diminished the platelet aggregation activity of the ADP. Depending on the relationship between ADP and intima extract concentrations aggregating activity could either be completely inhibited or inhibition abolished. Incubation of ADP with intima extract and subsequent separation of degradation products by paper chromatography, demonstrated a time-dependent breakdown of ADP with AMP, adenosine, inosine and hypoxanthine as metabolic products; ADP removal was complete. Collagen, thrombin and adrenaline aggregate platelets mainly by endogenous ADP of the release reaction. Results of experiments comparing inhibition of aggregation caused by premixing aggregating agent with intima extract, before exposure to platelets, and the sequential addition of first the intima extract and then aggregating agent to platelets, suggest that the inhibitory effect of intima extract results from ADP breakdown. It is suggested that this ADP degradation by intima extract may play a protective role in vivo by limiting the size of platelet aggregates forming at the site of minimal “wear and tear” vascular trauma.

Gradient-Enhanced Inverse-Detected NMR Techniquesfor Determination of 1H-15N Coupling Constants in 2,2-Dimethylpenta-3,4-dienal Derivatives

1997 ◽  
Vol 62 (11) ◽  
pp. 1747-1753 ◽  
Author(s):  
Radek Marek
Keyword(s):  
Double Bond ◽  
Chemical Shifts ◽  
Multiple Bond ◽  
Coupling Constants ◽  
Single Quantum ◽  
Nmr Techniques ◽  
Phase Sensitive ◽  
Heteronuclear Coupling

Determination of 15N chemical shifts and heteronuclear coupling constants of substituted 2,2-dimethylpenta-3,4-dienal hydrazones is presented. The chemical shifts were determined by gradient-enhanced inverse-detected NMR techniques and 1H-15N coupling constants were extracted from phase-sensitive gradient-enhanced single-quantum multiple bond correlation experiments. Stereospecific behaviour of the coupling constants 2J(1H,15N) and 1J(1H,13C) has been used to determine the configuration on a C=N double bond. The above-mentioned compounds exist predominantly as E isomers in deuteriochloroform.

Chemometric Analysis of Substituent Effects. VIII. Alternative Interpretation of Substituent Effects (AISE)

1995 ◽  
Vol 60 (9) ◽  
pp. 1502-1528 ◽  
Author(s):  
Oldřich Pytela
Keyword(s):  
Multiple Bond ◽  
Substituent Effects ◽  
Alternative Interpretation ◽  
Class I ◽  
Reaction Centre ◽  
Correlation Equations ◽  
Class Iii ◽  
Substituent Constant ◽  
Chemical Models ◽  
The Individual

Alternative interpretation of substituent effects (AISE) starts from the presumption that a substituent only possesses a single property described by a single substituent constant. This property is transmitted to the reaction centre by three different ways depending on the interaction type in the triad reaction centre - basic skeleton - substituent. For interpretation it is substantial whether or not the substituent has p electrons at the atom adjacent to the basic skeleton. If it has none, the substituent belongs to class I and operates only by its basic effect described by the mentioned single substituent constant. Substituents of class II possess a free electron pair at the atom adjacent to the basic skeleton, and those of class III have a multiple bond between the first and the second atoms which is polarized in the direction from the basic skeleton. Substituent effects in class I are described by a substituent constant identical with σI constant. Substituents in classes II and III show additional effects proportional to the same constant. Hence, a separate treatment of substituent effects in the individual classes provides three straight lines intersecting in a common point. Mathematically, the description of substituent effects in this approach is expressed by a family of lines with a single explaining variable. The point of intersection, which is referred to as the iso-effect point, is not identical with the classic standard substituent - hydrogen - but is near to CN substituent. The approach given has the advantage of adopting a single substituent constant whose scale can be adjusted relatively precisely. Its drawback (like in the case of the correlation equations derived from the principle of separation of substituent effects) lies in a more extensive set of substituents needed for a correlation. The AISE principle has been applied to 318 series of experimental data describing effects of 32 substituents in a large variety of chemical models (aliphatic, alicyclic, aromatic, heteroaromatic, with or without direct conjugation between reaction centre and substituent) in both chemical reactions and equilibria. A comparison with two other correlation relations with two and three substituent constants for interpretation of substituent effects based on the principle of separation of the individual substituent effects showed that the closeness of AISE based correlations is comparable with that of the correlation equations currently used. It was somewhat less successful in the models with direct conjugation between reaction centre and substituent but the AISE principle can be used even in these cases.

Multiple bond migration with participation of a protophilic agent

1997 ◽  
Vol 46 (10) ◽  
pp. 1677-1682 ◽  
Author(s):  
N. M. Vitkovskaya ◽  
V. B. Kobychev ◽  
A. B. Trofimov ◽  
B. A. Trofimov
Keyword(s):  
Multiple Bond

High-quality oligo-RNA synthesis using the new 2′-O-TEM protecting group by selectively quenching the addition of p-tolyl vinyl sulphone to exocyclic amino functions

2007 ◽  
Vol 85 (4) ◽  
pp. 293-301 ◽  
Author(s):  
Chuanzheng Zhou ◽  
Wimal Pathmasiri ◽  
Dmytro Honcharenko ◽  
Subhrangsu Chatterjee ◽  
Jharna Barman ◽  
...  
Keyword(s):  
Michael Addition ◽  
Chemical Biology ◽  
Rna Synthesis ◽  
Spectroscopic Analysis ◽  
Multiple Bond ◽  
Protecting Group ◽  
High Quality ◽  
Heteronuclear Multiple Bond Correlation ◽  
Michael Adducts

During the F–-promoted deprotection of the oligo–RNA, synthesized using our 2′-O-(4-tolylsulfonyl)ethoxymethyl (2′-O-TEM) group [Org. Biomol. Chem. 5, 333 (2007)], p-tolyl vinyl sulphone (TVS) is formed as a by-product. The TVS formed has been shown to react with the exocyclic amino functions of adenosine (A), guanosine (G), and cytidine (C) of the fully deprotected oligo–RNA to give undesirable adducts, which are then purified by HPLC and unambiguously characterized by 1H, 13C Heteronuclear Multiple Bond Correlation (HMBC) NMR and mass spectroscopic analysis. The relative nucleophilic reactivities of the nucleobases toward TVS have been found to be the following: N6–A > N4–C > N2–G > > N3–U. This reactivity of TVS toward RNA nucleobases to give various Michael adducts could, however, be suppressed by using various amines as scavengers. Among all these amines, morpholine and piperidine are the most efficient scavenger for TVS, which gave highly pure oligo–RNA even in the crude form and can be used directly in RNA chemical biology studies.Key words: RNA synthesis, RNA alkylation, p-tolyl vinyl sulphone, Michael addition.

Two-dimensional NMR studies of acrylate copolymers

2009 ◽  
Vol 81 (3) ◽  
pp. 389-415 ◽  
Author(s):  
A. S. Brar ◽  
Ashok Kumar Goyal ◽  
Sunita Hooda
Keyword(s):  
Methyl Methacrylate ◽  
Methyl Acrylate ◽  
Quantum Coherence ◽  
Multiple Bond ◽  
Microstructural Analysis ◽  
2D Nmr ◽  
Correlation Spectroscopy ◽  
Nmr Studies ◽  
Poly Methyl Methacrylate ◽  
Nmr Study

High-resolution NMR spectroscopy is the most versatile, reliable, and generally acceptable technique for the determination of the microstructure of polymers. 2D NMR techniques, along with 1D NMR, have more potential to study absolute configurational assignments and sequence distribution of copolymers. Physical and chemical properties of polymers are influenced fundamentally by their microstructure. We discuss the detailed microstructure analysis of a large number of homopolymers, copolymers, and terpolymers. 2D NMR study of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), and poly(methacrylonitrile) (PMAN) is discussed in this article. In addition to homopolymers, 2D heteronuclear single-quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple-bond correlation (HMBC) study of different copolymers such as poly(methyl methacrylate-co-methyl acrylate), poly(styrene-co-methyl methacrylate), and poly(methyl methacrylate-co-methacrylonitrile) have also been reported here. This in turn helps in microstructural analysis of terpolymers such as poly(methacrylonitrile-co-styrene-co-methyl methacrylate), poly(acrylonitrile-co-methyl methacrylate-co-methyl acrylate), and poly(ethylene-co-vinyl acetate-co-carbon monoxide).

scholarly journals Template-directed primer extension catalyzed by the Tetrahymena ribozyme.

1991 ◽  
Vol 11 (6) ◽  
pp. 3390-3394 ◽  
Author(s):  
D P Bartel ◽  
J A Doudna ◽  
N Usman ◽  
J W Szostak
Keyword(s):  
Rna Polymerase ◽  
Binding Site ◽  
Primer Extension ◽  
Mutant Enzyme ◽  
Base Pairs ◽  
Sequential Addition

The Tetrahymena ribozyme has been shown to catalyze an RNA polymerase-like reaction in which an RNA primer is extended by the sequential addition of pN nucleotides derived from GpN dinucleotides, where N = A, C, or U. Here, we show that this reaction is influenced by the presence of a template; bases that can form Watson-Crick base pairs with a template add as much as 25-fold more efficiently than mismatched bases. A mutant enzyme with an altered guanosine binding site can catalyze template-directed primer extension with all four bases when supplied with dinucleotides of the form 2-aminopurine-pN.

Sign in / Sign up

Export Citation Format

Share Document