Search results for " Synthesis"
showing 10 items of 1625 documents
Asymmetric Synthesis of Monofluorinated 1-Amino-1,2-dihydronaphthalene and 1,3-Amino Alcohol Derivatives.
2016
Enantioenriched 1-amino-4-fluoro-1,2-dihydronaphthalene derivatives are accessed via two complementary synthetic strategies. The careful optimization of the reaction conditions required for the elimination step in one route has allowed both the identification of an anchimerically assisted reaction pathway and, more importantly, access to a divergent reaction pathway toward fluorinated 1,3-amino alcohols from a common intermediate just by adjusting the number of equivalents of base used.
ChemInform Abstract: Asymmetric Synthesis of Monofluorinated 1-Amino-1,2-dihydronaphthalene and 1,3-Amino Alcohol Derivatives.
2016
Enantioenriched 1-amino-4-fluoro-1,2-dihydronaphthalene derivatives are accessed via two complementary synthetic strategies. The careful optimization of the reaction conditions required for the elimination step in one route has allowed both the identification of an anchimerically assisted reaction pathway and, more importantly, access to a divergent reaction pathway toward fluorinated 1,3-amino alcohols from a common intermediate just by adjusting the number of equivalents of base used.
Anodic Oxidation as an Enabling Tool for the Synthesis of Natural Products
2020
Electrochemistry provides a valuable toolbox for organic synthesis and offers an appealing, environmentally benign alternative to the use of stoichiometric quantities of chemical oxidants or reductants. Its potential to control current efficiency along with providing alternative reaction conditions in a classical sense makes electrochemistry a suitable method for large-scale industrial transformations as well as for laboratory applications in the synthesis of complex molecular architectures. Even though research in this field has intensified over the recent decades, many synthetic chemists still hesitate to add electroorganic reactions to their standard repertoire, and hence, the full poten…
Reactivity of β-amino alcohols against dialkyl oxalate: synthesis and mechanism study in the formation of substituted oxalamide and/or morpholine-2,3…
2012
The reactivity of various β-amino alcohols with dialkyl oxalates, in several reaction conditions, has been investigated. Linear disubstituted oxalamides were obtained with primary β-amino alcohols and linear tetrasubstituted oxalamides, or a mixture of linear tetrasubstituted oxalamides and cyclic morpholine-2,3-diones were obtained with N-substituted β-amino alcohols. A DFT study of the possible mechanism has been made. The theoretical results indicate that these reactions are not kinetically controlled, there is an equilibrium between all species and therefore follow a thermodynamic control. The different behavior between the primary β-amino alcohols and N-methyl β-amino alcohols is due t…
Electrifying Organic Synthesis
2018
Abstract The direct synthetic organic use of electricity is currently experiencing a renaissance. More synthetically oriented laboratories working in this area are exploiting both novel and more traditional concepts, paving the way to broader applications of this niche technology. As only electrons serve as reagents, the generation of reagent waste is efficiently avoided. Moreover, stoichiometric reagents can be regenerated and allow a transformation to be conducted in an electrocatalytic fashion. However, the application of electroorganic transformations is more than minimizing the waste footprint, it rather gives rise to inherently safe processes, reduces the number of steps of many synth…
N‐Heterocyclic Carbene Catalyzed Quadruple Domino Reactions: Asymmetric Synthesis of Cyclopenta[ c ]chromenones
2018
An N-heterocyclic carbene catalyzed domino sequence via α,β-unsaturated acyl azolium intermediates has been developed. This strategy provides a convenient enantioselective route to functionalized tricyclic coumarin derivatives and cyclopentanes. DFT studies and control experiments were performed to gain better insight into the reaction mechanism.
Enantioselective Palladium-Catalyzed Oxidative β,β-Fluoroarylation of α,β-Unsaturated Carbonyl Derivatives
2016
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The site-selective palladium-catalyzed three-component coupling of deactivated alkenes, arylboronic acids, and N-fluorobenzenesulfonimide is disclosed herein. The developed methodology establishes a general, modular, and step-economical approach to the stereoselective β-fluorination of α,β-unsaturated systems.
Assisted self-sustaining combustion reaction in the Fe–Si system: Mechanical and chemical activation
2007
Abstract This work presents original investigations carried out to improve the activated self-propagating high-temperature synthesis (SHS) process in the Fe–Si system: different ignition modes are tested (volume heating as opposed to a local ignition source), and the use of additive is considered in order to enhance the SHS type reactivity in the Fe–Si system. When 20 wt.% of KNO 3 is added to the reactive mixture, the fast (>20 mm s −1 ), stable and self-sustaining combustion reaction produces a very fine FeSi + α-FeSi 2 structure. Infrared thermography (IR) as well as post-mortem analysis (SEM, EDXS, XRD) was used to understand the mechanism behind the chemical activation process when KNO…
Microstructural study of titanium carbonitride elaborated by combustion synthesis
2007
Abstract The self-propagating high-temperature synthesis (S.H.S.) process, which is promising for the fabrication of ceramic materials, was chosen to elaborate titanium carbonitride materials. The influence of parameters such as nitrogen gas pressure and carbon ratio on the microstructure was studied. A single phase product of Ti(C,N) is obtained for a carbon ratio under 15 at.% and a nitrogen pressure of 36 MPa. The increase of the carbon ratio corresponds to a decrease of the maximum temperature reached during the synthesis. Time resolved X-ray diffraction measurements (TRXRD) with the synchrotron radiation were used to determine the reaction mechanisms. We could observe that the synthesi…
New reaction of 1H-pyrazoles with selenium dioxide: one-pot synthesis of bis(1H-pyrazol-4-yl)selenides
2010
Abstract A novel reaction between 3- and 3,5-substituted pyrazoles with selenium dioxide proceeds with formation of bis(3R,5R′-1H-pyrazol-4-yl)selenides in high yield. On this basis, an efficient one-pot synthetic procedure has been developed. In the case of the unsubstituted pyrazole a selenonium compound has been obtained. The identity and structure of the isolated selenium derivatives have been confirmed by spectral methods and their molecular structures investigated by X-ray analysis.