Search results for "Reaction"

A new mechanism for internal nucleophilic substitution reactions

2018

A new mechanism for the classic internal nucleophilic substitution reactions SNi by means of computational studies in the gas-phase, DCM and acetonitrile is reported. Despite the importance of the SNi mechanism, since the mid-1990s this mechanism has remained unexplored. This study focused mainly on the comparison between the mechanisms postulated to date for the SNi reactions and a new mechanism suggested by us that fits better the experimental observations. This comparative study has been applied to the conversion of ethyl, neopentyl, isopropyl and tert-butyl chlorosulfites into the corresponding alkyl chlorides. This new mechanism occurs through two transition structures. For primary and…

Ligand substitution in cis-bis(acetonitrile)tetrachlororhenium(IV) complex with N,N-dimethylformamide and N,N-dimethylacetamide

2018

Abstract The preparation, crystal structures, and magnetic properties of two novel mononuclear ReIV complexes of formula cis-[ReIVCl4(dmf)2] (1) and cis-[ReIVCl4(dma)2] (2) (dmf = N,N-dimethylformamide and dma = N,N-dimethylacetamide) have been studied. Both ReIV systems were synthesized through ligand substitution reactions from the cis-[ReIVCl4(MeCN)2] precursor, upon heating in the employed solvent. 1 and 2 crystallize in the monoclinic crystal system with space group C2/c. Each ReIV ion exhibits a distorted octahedral environment, being bonded by two oxygen atoms from two dmf (1) and dma (2) molecules and four chloride ions. In the crystal lattice of 1 and 2, the mononuclear ReIV comple…

Synthesis and Topological Determination of Hexakis-Substituted 1,4-Ditritylbenzene and Nonakis-Substituted 1,3,5-Tritritylbenzene Derivatives: Buildi…

2012

Based on trityl moieties, novel organic building blocks have been prepared and structurally investigated. Substituted hexaphenyl-p-xylene (1,4-ditritylbenzene) as well as extended analogues thereof were prepared. Furthermore, a new family based on a 1,3,5-tritritylbenzene motif, connecting three trityl groups through a formal mesitylene unit, was developed. Both families were further converted through six- and nine-fold substitution reactions, respectively, to yield potent molecular building blocks for supramolecular assemblies.

Cu(I) complexes with diethoxyphosphoryl-1,10-phenanthrolines in catalysis of C–C and C–heteroatom bonds formation

2015

Abstract Diethoxyphosphoryl substituted 1,10-phenanthroline copper(I) complexes were tested as catalysts in the Sonogashira-type reaction, α-arylation of phosphoryl-stabilized C–H acids, C–N, C–P bond forming reactions (substitution reactions) and in the reaction of phenylacetylene and bis(pinacolato)diboron (addition reaction). The complexes demonstrate fairly high catalytic activity and in some cases their efficiency is superior to that of the parent Cu(phen)(PPh 3 )Br (phen = phenanthroline).

Use of a bulky phosphine of weak σ-donicity with palladium as a versatile and highly-active catalytic system: allylation and arylation coupling react…

2005

Abstract Carbon–carbon(sp2–sp2 and sp1–sp2) and carbon–nitrogen (nucleophilic allylation) coupling processes are promoted by a catalytic system containing [PdCl(η3–C3H5)]2 with the new ferrocenyl bis(difurylphosphine) 1,1′-bis[di(5-methyl-2-furyl)phosphino]ferrocene, Fc[P(FuMe)2]2. Starting from aryl bromides or allylic acetates this versatile catalyst system may be used at low palladium loadings (10−1–10−4 mol%) in some Heck, Suzuki, Sonogashira and allylic amination reactions to give cross-coupled products in excellent yield. Remarkably high activity is obtained in allylic substitution reactions, providing a significant impetus for the development of bulky phosphines possessing weak σ-don…

N1-Functionalized Indole-Phosphane Oxazoline (IndPHOX) Ligands in Asymmetric Allylic Substitution Reactions

2012

N-Functionalized IndPHOX ligands bearing various groups have been synthesized and the effects of the N1-substituent on the reaction rate, yield, and asymmetric induction in a palladium-catalyzed allylic substitution reaction are reported. The presence of an oxygen atom in the ligands, namely an N-MOM or N-THP group, led to enhancement of the enantioselectivity in the allylic amination reaction. In addition, a ligand with a chiral oxazoline ring at C-1 and a phosphane substituent at C-2 provided high enantioselectivity in good yield in an asymmetric allylic alkylation reaction.

ChemInform Abstract: N1-Functionalized Indole-Phosphane Oxazoline (IndPHOX) Ligands in Asymmetric Allylic Substitution Reactions.

2012

N-Functionalized IndPHOX ligands bearing various groups have been synthesized and the effects of the N1-substituent on the reaction rate, yield, and asymmetric induction in a palladium-catalyzed allylic substitution reaction are reported. The presence of an oxygen atom in the ligands, namely an N-MOM or N-THP group, led to enhancement of the enantioselectivity in the allylic amination reaction. In addition, a ligand with a chiral oxazoline ring at C-1 and a phosphane substituent at C-2 provided high enantioselectivity in good yield in an asymmetric allylic alkylation reaction.

Rate Effects of AOT-Stabilized Microemulsions on Reactions of Ligand Substitution in Cationic Palladium(II) Complexes

1998

Rate data for the substitution reactions of the coordinated ligand X (=2,2‘-bipyridine or 4,4‘-dimethyl-2,2‘-bipyridine) of the palladium(II) complex [Pd(en)X]2+, where en = ethylenediamine, by en or N,N-dimethylethylenediamine in heptane−AOT−water microemulsions have been obtained at 25.0 °C as a function of the AOT concentration at the constant R (=[H2O]/[AOT]) values of 3, 8, and 20 or 30. The overall second-order rate constants are higher in microemulsions than in bulk water and decrease significantly as both the AOT concentration (at constant R) and the molar ratio R (at a given [AOT]) increase. The quantitative analysis of the kinetic data, made by applying the pseudophase model, lead…

Frontispiece: Fluorine‐Containing Drugs Approved by the FDA in 2018

2019

INSERTION OF ISOCYANIDES INTO THE PALLADIUM CARBON BOND OF C-2-PALLADATED HETEROCYCLES - SYNTHESIS OF TRANS-[PDCL(C(RN)=NR) (PPH3)2] COMPLEXES (RN = …

1985

The titles complexes trans-[PdCl{C(RN)NR}(PPh3)2] (RN = 2-pyridyl (2-py), R = p-C6H4OMe, Me; RN = 2-pyrazyl (2-pyz), R = p-C6H4OMe) can be prepared by reaction of the N-protonated compounds, cis-[PdCl2(RNH)(PPh3] (RNH = 2-pyridylium (2-pyH) or 2-pyrazylium (2-pyzH) group), with PPh3, followed by addition of the isocyanide CNR and deprotonation with triethylamine, in a molar ratio Pd/PPh3/CNR/NEt3 of 1/1/1/1.1. The reaction sequence involves the successive formation of the cationic intermediates trans-[PdCl(RNH)(PPh3)2]+, trans-[Pd(RNH)(CNR)(PPh3)2]2+ and trans-[Pd(RN)(CNR)(PPh3)2]+, which were isolated and characterized as perchlorate salts for RN = 2-pyridyl. In the final step the coordin…