Computational Studies of Nucleophilic Substitution at Carbonyl Carbon:  the SN2 Mechanism versus the Tetrahedral Intermediate in Organic Synthesis

2004 ◽  
Vol 69 (21) ◽  
pp. 7317-7328 ◽  
Author(s):  
Joseph M. Fox ◽  
Olga Dmitrenko ◽  
Lian-an Liao ◽  
Robert D. Bach
Keyword(s):  
Nucleophilic Substitution ◽  
Organic Synthesis ◽  
Computational Studies ◽  
Carbonyl Carbon ◽  
Tetrahedral Intermediate

scholarly journals Structural basis of the stereoselective formation of the spirooxindole ring in the biosynthesis of citrinadins

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhiwen Liu ◽  
Fanglong Zhao ◽  
Boyang Zhao ◽  
Jie Yang ◽  
Joseph Ferrara ◽  
...  
Keyword(s):  
High Resolution ◽  
Organic Synthesis ◽  
Indole Alkaloids ◽  
Site Directed Mutagenesis ◽  
Structural Basis ◽  
Directed Mutagenesis ◽  
Computational Studies ◽  
X Ray ◽  
Evolutionary Branch ◽  
Catalytic Mechanisms

AbstractPrenylated indole alkaloids featuring spirooxindole rings possess a 3R or 3S carbon stereocenter, which determines the bioactivities of these compounds. Despite the stereoselective advantages of spirooxindole biosynthesis compared with those of organic synthesis, the biocatalytic mechanism for controlling the 3R or 3S-spirooxindole formation has been elusive. Here, we report an oxygenase/semipinacolase CtdE that specifies the 3S-spirooxindole construction in the biosynthesis of 21R-citrinadin A. High-resolution X-ray crystal structures of CtdE with the substrate and cofactor, together with site-directed mutagenesis and computational studies, illustrate the catalytic mechanisms for the possible β-face epoxidation followed by a regioselective collapse of the epoxide intermediate, which triggers semipinacol rearrangement to form the 3S-spirooxindole. Comparing CtdE with PhqK, which catalyzes the formation of the 3R-spirooxindole, we reveal an evolutionary branch of CtdE in specific 3S spirocyclization. Our study provides deeper insights into the stereoselective catalytic machinery, which is important for the biocatalysis design to synthesize spirooxindole pharmaceuticals.

scholarly journals Nucleophilic C–H functionalization of arenes: a new logic of organic synthesis

2017 ◽  
Vol 89 (8) ◽  
pp. 1195-1208 ◽  
Author(s):  
Oleg N. Chupakhin ◽  
Valery N. Charushin
Keyword(s):  
Electron Transfer ◽  
Green Chemistry ◽  
Nucleophilic Substitution ◽  
Organic Synthesis ◽  
Nucleophilic Substitution Of Hydrogen ◽  
Metal Free ◽  
Hydride Ion ◽  
Electrochemical Modeling ◽  
Leaving Groups ◽  
Concept Change

AbstractDirect metal-free C–H functionalization of arenes with nucleophiles is a new chapter in the chemistry of aromatics. Comprehensive studies on nucleophilic substitution of hydrogen in arenes (the SNH reactions), including mechanisms, intermediates, mathematic and electrochemical modeling, kinetics, electron-transfer, etc. have shown that this is not the hydride ion, but C–H proton is departed, and this process is facilitated by the presence of an appropriate oxidant or an auxiliary group. The SNH reactions, as a part of the general C–H functionalization concept, change the logic of organic synthesis. They open new opportunities, avoiding incorporation of good leaving groups or other auxiliaries in an aromatic ring, as a prefunctionalization step, thus providing a better correspondence to the principles of green chemistry.

scholarly journals N-Heterocyclic Carbene Mediated Organocatalysis Reactions

2021 ◽  
Author(s):  
Yatheesh Narayana ◽  
Sandhya N. C. ◽  
H.E. Dinesh ◽  
Sridhar B. Thimmaiah ◽  
Kanchugarakoppal S. Rangappa ◽  
...  
Keyword(s):  
Transition Metals ◽  
Carbonyl Group ◽  
Organic Synthesis ◽  
Practical Significance ◽  
Theoretical Studies ◽  
Carbonyl Carbon ◽  
Main Group Elements ◽  
Catalyzed Reactions ◽  
Electrophilic Character ◽  
Experimental And Theoretical Studies

Arduengo et al., isolated the first ‘bottleable’ carbene, the first N-heterocyclic carbene (NHC) 1,3-di(adamantyl)imidazol-2-ylidene resulted to an explosion of experimental and theoretical studies of novel NHCs being synthesized and analyzed have huge practical significance. These compounds emerged as successful ligands for coordinating transition metals, the complexes with NHC show diverse applications in the field of catalysis and organic transformation, NHC as ligand to main group elements and their properties and applications. Here this chapter provides the concise overview of N-heterocycle carbene as an organocatalyst that provides different organic transformation on to a carbonyl group. The majority of the NHC catalyzed reactions are employed in the phenomenon of reversing the electrophilic character of carbonyl carbon to nucleophilic carbon (umpolung activity) on coordination suggests benzoin, Stetter and hydroacylation reactions. Also, non-umpolung activity of bis-electrophile α,β-unsaturated acylazoliums reaction with suitable bis-nucleophiles in the organic synthesis have been studied.

Activation of C–F, Si–F, and S–F Bonds by N-Heterocyclic Carbenes and Their Isoelectronic Analogues

Synlett ◽  
2020 ◽  
Vol 31 (14) ◽  
pp. 1349-1360 ◽  
Author(s):  
Eunsung Lee ◽  
Ewa Pietrasiak
Keyword(s):  
Nucleophilic Substitution ◽  
Organic Synthesis ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Oxidative Addition ◽  
Main Group ◽  
Heterocyclic Carbenes ◽  
Full Potential ◽  
Short Summary ◽  
Special Case

Reactions involving C–F, Si–F, and S–F bond cleavage with N-heterocyclic carbenes and isoelectronic species are reviewed. Most examples involve activation of aromatic C–F bond via an SNAr pathway and nucleophilic substitution of fluorine in electron-deficient olefins. The mechanism of the C–F bond activation depends on the reaction partners and the reaction can proceed via addition–elimination, oxidative addition (concerted or stepwise) or metathesis. The adducts formed upon substitution find applications in organic synthesis, as ligands and as stable radical precursors, but in most cases, their full potential remains unexplored.1 Introduction1.1 The C–F Bond1.2 C–F Bond Activation: A Short Summary1.3 C–F Bond Activation: A Special Case of SNAr1.4 N-Heterocyclic Carbenes (NHCs)1.5 The Purpose of this Article2 C–F bond Activation in Acyl Fluorides3 Activation of Vinylic C–F Bonds4 Activation of Aromatic C–F Bonds5 X–F Bond Activation (X = S or Si)6 C–F Bond Activation by Main Group Compounds Isoelectronic with NHCs7 Conclusions and Outlook

Application of Vicarious Nucleophilic Substitution in Organic Synthesis

1997 ◽  
Vol 1997 (9) ◽  
pp. 1805-1816 ◽  
Author(s):  
Mieczyslaw M??kosza ◽  
Krzysztof Wojciechowski
Keyword(s):  
Nucleophilic Substitution ◽  
Organic Synthesis ◽  
Vicarious Nucleophilic Substitution

scholarly journals Boranes in Organic Chemistry 3. α-, β- and γ-Haloalkylboranes: The Perspective Vehicles for Organic Synthesis

2016 ◽  
Vol 5 (2) ◽  
pp. 83 ◽  
Author(s):  
V.M. Dembitsky ◽  
G.A. Tolstikov ◽  
M. Srebnik
Keyword(s):  
Organic Chemistry ◽  
Nucleophilic Substitution ◽  
Organic Synthesis ◽  
General Scheme ◽  
Radical Addition ◽  
Boronic Esters ◽  
Methods Of Synthesis ◽  
Boron Tribromide ◽  
Derivatives Of ◽  
Acid Esters

<p>The methods of synthesis of α− and β−haloalkylboranes, including chloration of alkylboronic acid esters, additive bromation and chloration of esters of vinyl- and alkenylboronic acids, addition of bromine to trivinylborazines have been considered. The reactions of radical addition of polyhaloidmethanes to vinylboranes, α− and β−unsaturated boronic esters, B-vinyl-B-arylboronic esters, B-trivinyl-B-triarylborazines were discussed. The hydroboration of acetylenic halogenides of dicycloalkylboranes, which led to halocontaining derivatives of dialkylvinylborane was separately considered. The examples of hydroboration of halogenides of allyl and vinyl types are presented. The reaction of dienic synthesis, which takes place between vinylchloroboranes or vinylboronic esters and tetra- or hexachlorocyclopentadienes has been discussed. The reaction of alkenes and allenes with boron tribromide was described. The Markovnikov and non-Markovnikov hydrobromation of boron vinylderivatives has been envisaged. The approaches to the synthesis of perfluoroalkylboranes on the base of hydroboration of perfluoroalkenes have been discussed. The methods of the synthesis of boronates, containing halogetaryl substituents, have been performed. The reactions of hydroboration of halogenides of allylic and propargylic types by 9-borabicyclononane have been shown. The regio- and stereoselectivity of the reaction has been discussed. The examples of the synthesis of boranes of the norbornene type were presented. The reaction of boroallylilation of allyl- and propargylhalogenides leading to the derivatives of 3-bora-bicyclo[3,3,1]-nonane has been discussed. Some directions of using of haloidalkylboranes in the synthesis have been discussed. The examples of nucleophilic substitution leading to oxyalkyl- and azidoalkylboranes have been presented. The route of obtaining of alcohols from α−haloidalkylboranes has been shown. The general scheme of synthesis of α−aminoboronic acids was perfomed. The general approach to the synthesis of allenes on the base of hydroboration products of propargyl halogenides has been discussed. The schemes of synthesis of 1,4-disubstituted-1,2,3-butatrienes are presented. The wide using reaction of introducing of vinylic group into substituent, bonding with boron atom in molecules of dialkylvinylboranes, was discussed. The reactions of new C-C bonds formation, based on the action of iodine on the alkylvinylboronates leading to 1,3-dienes and alkylidencyclanes have been shown. Τhe route of the synthesis of cyclopropanes from β−haloidalkylboranes has been discussed.</p>

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