ChemInform Abstract: URANIUM-CARBON MULTIPLE BOND CHEMISTRY. 2. COUPLING OF BRIDGING AND TERMINAL CARBONYLS IN THE FORMATION OF AN IRON η1:η3-ALLYL COMPLEX

1984 ◽  
Vol 15 (6) ◽  
Author(s):  
R. E. CRAMER ◽  
K. T. HIGA ◽  
S. L. PRUSKIN ◽  
J. W. GILJE
Keyword(s):  
Multiple Bond ◽  
Allyl Complex

Uranium-carbon multiple bond chemistry. 2. Coupling of bridging and terminal carbonyls in the formation of an iron .eta.1:.eta.3-allyl complex

1983 ◽  
Vol 105 (22) ◽  
pp. 6749-6750 ◽  
Author(s):  
Roger E. Cramer ◽  
Kelvin T. Higa ◽  
Steven L. Pruskin ◽  
John W. Gilje
Keyword(s):  
Multiple Bond ◽  
Allyl Complex

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.

ChemInform Abstract: Synthesis, Structure and Catalytic Activity of a Bimacrocyclic NHC Palladium Allyl Complex.

ChemInform ◽  
2008 ◽  
Vol 39 (52) ◽  
Author(s):  
Ole Winkelmann ◽  
Christian Naether ◽  
Ulrich Luening
Keyword(s):  
Catalytic Activity ◽  
Allyl Complex

Bis[1,3-bis(trimethylsilyl)allyl]cobalt(II), a stable electron-deficient allyl complex

2004 ◽  
Vol 60 (10) ◽  
pp. m507-m508 ◽  
Author(s):  
J. Dominic Smith ◽  
Keith T. Quisenberry ◽  
Timothy P. Hanusa ◽  
William W. Brennessel
Keyword(s):  
Allyl Complex

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.

Sign in / Sign up

Export Citation Format

Share Document