Structure and reactivity of lithium diphenylamide. Role of aggregates, mixed aggregates, monomers, and free ions on the rates and selectivities of N-alkylation and E2 elimination

1988 ◽  
Vol 110 (16) ◽  
pp. 5524-5533 ◽  
Author(s):  
Jeffrey S. DePue ◽  
David B. Collum
Keyword(s):  
Free Ions ◽  
Mixed Aggregates

Role of Organolithium Aggregates and Mixed Aggregates in Organolithium Mechanisms

2013 ◽  
Vol 113 (9) ◽  
pp. 7130-7178 ◽  
Author(s):  
Hans J. Reich
Keyword(s):  
Mixed Aggregates

Polymorphonuclear Leukocyte-Platelet Interaction: Role of P-Selectin in Thromboxane B2 and Leukotriene C4 Cooperative Synthesis

1994 ◽  
Vol 72 (03) ◽  
pp. 450-456 ◽  
Author(s):  
Norma Maugeri ◽  
Virgilio Evangelista ◽  
Antonio Celardo ◽  
Giuseppe Dell’Elba ◽  
Nicola Martelli ◽  
...  
Keyword(s):  
Cell Aggregation ◽  
Inhibitory Effect ◽  
Cathepsin G ◽  
Cell Contact ◽  
Mixed Cell ◽  
Platelet Surface ◽  
Mixed Aggregates ◽  
Transcellular Metabolism ◽  
Cell Cell

SummaryIn PMN/platelet suspensions stimulated by fMLP giant mixed aggregates are formed and TxB2 and LTC4 are synthesized as the result of the cooperation in the arachidonic acid (AA) metabolism during cell/cell contact. PMN-derived cathepsin G induced the expression of P-selectin on platelet surface. GE12, an antibody against P-selectin, significantly reduced mixed cell aggregates. GE12 did not affect platelet aggregation induced by PMN-derived supernatants, indicating that the inhibitory effect of GE12 on mixed cell aggregation depends on inhibition of PMN/platelet adhesion. GE12 significantly reduced TxB2 and LTC4 production in PMN/platelet mixed cell suspensions stimulated by fMLP. As previously reported, synthesis of 3H-TxB2 in 3H-AA-labeled PMN/unlabeled platelets indicates that platelets utilize 3H-AA from PMN. 3H-LTC4 production in unlabeled PMN/3H-AA-labeled platelets indicates that bidirectional routes are utilized in this system for LTC4 synthesis. GE12 significantly reduced 3H-TxB2 and 3H-LTC4 synthesis. These results show that cathepsin G released by activated PMN induces the expression of P-selectin on platelet membrane: this adhesive glycoprotein modulates cell-cell contact and transcellular metabolism of AA.

ChemInform Abstract: Role of Organolithium Aggregates and Mixed Aggregates in Organolithium Mechanisms

ChemInform ◽  
2013 ◽  
Vol 44 (45) ◽  
pp. no-no
Author(s):  
Hans J. Reich
Keyword(s):  
Mixed Aggregates

The role of free ions in reactions of olefins with soluble complex catalysts

2007 ◽  
Vol 16 (4) ◽  
pp. 2333-2339 ◽  
Author(s):  
F. S. Dyachkovskii ◽  
A. K. Shilova ◽  
A. E. Shilov
Keyword(s):  
Soluble Complex ◽  
Free Ions

3-Aminopyrrolidine lithium amides as chiral ligands for alkyllithium derivatives: Synthesis, NMR analysis, and computational study of their mixed aggregates

2006 ◽  
Vol 78 (2) ◽  
pp. 321-331 ◽  
Author(s):  
Anne Harrison-Marchand ◽  
Jean-Yves Valnot ◽  
Aline Corruble ◽  
Nicolas Duguet ◽  
Hassan Oulyadi ◽  
...  
Keyword(s):  
Computational Study ◽  
Ligand Design ◽  
Model Reaction ◽  
Chiral Ligands ◽  
Nmr Analysis ◽  
Simplified Models ◽  
Lithium Amides ◽  
Mixed Aggregates

An overview of the role of 3-aminopyrrolidine lithium amides (3-APLi's) as chiral ligands for alkyllithiums (AlkLi's) is presented. Synthetic developments as well as NMR characterizations and computational interpretations have been simultaneously and complementarily conducted to improve the ligand design for a model reaction that is the condensation of AlkLi's on o-tolualdehyde, for which enantiomeric excesses up to 80 % were obtained. This study describes the whole chain going from the synthesis of the chiral 3-aminopyrrolidines (3-APs) (18 different 3-APs synthesized) to the characterization of the noncovalent mixed aggregates resulting from the interaction between the organolithium partners (3-APLi:AlkLi). Finally, the docking of the aldehyde on one lithium of the aggregate was analyzed by theoretical means on simplified models, in an attempt to understand the structure of the fully loaded pretransition complexes.

scholarly journals Anionic Snieckus−Fries Rearrangement: Solvent Effects and Role of Mixed Aggregates

2008 ◽  
Vol 130 (41) ◽  
pp. 13709-13717 ◽  
Author(s):  
Jason C. Riggs ◽  
Kanwal J. Singh ◽  
Ma Yun ◽  
David B. Collum
Keyword(s):  
Solvent Effects ◽  
Fries Rearrangement ◽  
Mixed Aggregates

scholarly journals Methylxanthines (caffeine, pentoxifylline and theophylline) decrease the mutagenic effect of daunomycin, doxorubicin and mitoxantrone.

2005 ◽  
Vol 52 (4) ◽  
pp. 923-926 ◽  
Author(s):  
Jacek Piosik ◽  
Anna Gwizdek-Wiśniewska ◽  
Katarzyna Ulanowska ◽  
Jakub Ochociński ◽  
Agata Czyz ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Mutagenic Effect ◽  
Spectrophotometric Titration ◽  
Stacking Interactions ◽  
Electron Systems ◽  
Cytotoxic Effects ◽  
Aromatic Molecules ◽  
Mixed Aggregates ◽  
Polycyclic Aromatic

Previously performed experiments showed that methylxanthines, especially caffeine, may protect cells against cytostatic or cytotoxic effects of several aromatic compounds. One of the proposed mechanisms of this protection is based on stacking interactions between pi electron systems of polycyclic aromatic molecules. In this work, we demonstrate that caffeine and other methylxanthines--pentoxifylline and theophylline--significantly decrease mutagenicity of the anticancer aromatic drugs daunomycin, doxorubicin and mitoxantrone. The spectrophotometric titration of these aromatic compounds by methylxanthines indicated formation of mixed aggregates. The concentrations of free active forms of the drugs decreased when the concentrations of methylxanthines increased in the mixture. Therefore, likely methylxanthines may play a role of scavengers of the free active forms of daunomycin, doxorubicin and mitoxantrone.

Effects of the Nucleophile Structure on the Mechanisms of Reaction of 1-Chloro-2,4-dinitrobenzene with Aromatic Amines in Aprotic Solvents

1999 ◽  
Vol 64 (10) ◽  
pp. 1583-1593 ◽  
Author(s):  
Norma Sbarbati Nudelman ◽  
Cecilia E. Silvana Alvaro ◽  
Monica Savini ◽  
Viviana Nicotra ◽  
Jeannette Yankelevich
Keyword(s):  
Hydrogen Bond ◽  
Tertiary Amine ◽  
Aromatic Amines ◽  
Order Rate Constant ◽  
Aprotic Solvents ◽  
Nucleophilic Substitutions ◽  
Hydrogen Bond Acceptor ◽  
Mixed Aggregates ◽  
Kinetics Of

The kinetics of reactions of 1-chloro-2,4-dinitrobenzene with aniline and several substituted aromatic amines, B, in toluene shows a quadratic dependence of the second-order rate constant, kA, on [B], which is preserved even in the presence of increasing amounts of dimethylaniline, while the reaction with N-methylaniline shows a linear dependence of kA vs [B]. All these results are interpreted by the "dimer nucleophile" mechanism, and confirmed by the effects of a non-nucleophilic hydrogen bond acceptor tertiary amine which show the relevance of the structure of the nucleophile and the role of mixed aggregates in defining the mechanisms of aromatic nucleophilic substitutions with amines in aprotic solvents.

Sign in / Sign up

Export Citation Format

Share Document