alkyl halides
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2022 ◽  
Author(s):  
Ben Niu ◽  
Krishnakumar Sachidanandan ◽  
Bryan G. Blackburn ◽  
Maria Victoria Cooke ◽  
Sébastien Laulhé

2022 ◽  
Author(s):  
Jose Aleman

Abstract Herein, we report, for the first time, a general, facile and environmentally friendly Minisci-type alkylation of N-heteroarenes under simple and straightforward electrochemical conditions using widely available alkyl halides as radical precursors. Primary, secondary and tertiary alkyl radicals have shown to be efficiently generated and coupled with a large variety of N-heteroarenes. The method presents a very high functional group tolerance, including various heterocyclic-based natural products, which highlights the robustness of the methodology. This applicability has been further proved in the synthesis of various interesting biologically valuable building blocks. In addition, we have proposed a mechanism based on different proofs and electrochemical evidences.


2021 ◽  
pp. 1-26
Author(s):  
Panayiotis V. Ioannou

Contrary to P(V) compounds, As(V) compounds can very easily reduced by thiols to As(III) thiolates that are deemed to play a central role in the metabolism of arsenic and therefore a review on the preparation and properties of the title thiolates can be of interest. The preparation of trithioarsenites, dithioarsonites and thioarsinites involves reactions of a thiol with a proper As(V) or As(III) precursor via 4-centered transition states or a thiolate by SN2 mechanisms. Convenient precursors are the solids As2O3, arsonic and arsinic acids, although for the latter two acids the separation of the product from the co-produced disulfides can be problematic. Only a few crystal structures have been reported and involve only trithioarsenites. From their chemical properties, the hydrolyses, transthiolations and air oxidations are of particular interest from mechanistic and biochemical/biological points of view. Their nucleophilicity towards alkyl halides and acyl derivatives revealed unexpected behavior. Although these molecules have many free electron pairs only three reports were found pertaining to their reaction with metal cations (Hg2+) and metal carbonyls; the mercuric complexes being not characterized. Only a few studies appeared for the action of the title compounds towards enzymes, while the patent literature revealed that they have bactericidal, fungicidal and insecticidal activities for agricultural applications, some have antiparasitic activity on animals and a few are carcinostatic.


2021 ◽  
Author(s):  
Song Lin ◽  
Wen Zhang ◽  
Lingxiang Lu ◽  
Wendy Zhang ◽  
Jose Mondragon ◽  
...  

Recent research in medicinal chemistry suggests a correlation between an increase in the fraction of sp3 carbons in drug candidates with their improved success rate in clinical trials. As such, the development of robust and selective methods for the construction of C(sp3)-C(sp3) bonds remains a critical problem in modern organic chemistry. Owing to the broad availability and synthetic accessibility of alkyl halides, their direct cross coupling—commonly known as cross-electrophile coupling (XEC)—provides a promising route toward this objective. However, achieving high selectivity in C(sp3)-C(sp3) XEC remains a largely unmet challenge. Herein, we employ electrochemistry to achieve the differential activation of alkyl halides by exploiting their disparate electronic and steric properties. Specifically, the selective cathodic reduction of a more substituted alkyl halide gives rise to a carbanion, which undergoes preferential coupling with a less substituted alkyl halide via bimolecular nucleophilic substitution (SN2) to forge a new C–C bond. This transition-metal free protocol enables the efficient XEC of a variety of functionalized and unactivated alkyl electrophiles and exhibits substantially improved chemoselectivity versus existing methodologies.


2021 ◽  
Author(s):  
Song Lin ◽  
Wen Zhang ◽  
Lingxiang Lu ◽  
Wendy Zhang ◽  
Jose Mondragon ◽  
...  

Recent research in medicinal chemistry suggests a correlation between an increase in the fraction of sp3 carbons in drug candidates with their improved success rate in clinical trials. As such, the development of robust and selective methods for the construction of C(sp3)-C(sp3) bonds remains a critical problem in modern organic chemistry. Owing to the broad availability and synthetic accessibility of alkyl halides, their direct cross coupling—commonly known as cross-electrophile coupling (XEC)—provides a promising route toward this objective. However, achieving high selectivity in C(sp3)-C(sp3) XEC remains a largely unmet challenge. Herein, we employ electrochemistry to achieve the differential activation of alkyl halides by exploiting their disparate electronic and steric properties. Specifically, the selective cathodic reduction of a more substituted alkyl halide gives rise to a carbanion, which undergoes preferential coupling with a less substituted alkyl halide via bimolecular nucleophilic substitution (SN2) to forge a new C–C bond. This transition-metal free protocol enables the efficient XEC of a variety of functionalized and unactivated alkyl electrophiles and exhibits substantially improved chemoselectivity versus existing methodologies.


2021 ◽  
Author(s):  
Nathaniel R. Braffman ◽  
Terry B. Ruskoski ◽  
Katherine M. Davis ◽  
Nate Glasser ◽  
Cassidy Johnson ◽  
...  

AbstractThe cyanobacterial enzyme CylK assembles the cylindrocyclophane natural products by performing two unusual alkylation reactions, forming new carbon-carbon bonds between aromatic rings and secondary alkyl halide substrates. This transformation is unprecedented in biology and the structure and mechanism of CylK are unknown. Here, we report x-ray crystal structures of CylK, revealing a distinctive fusion of a Ca2+ binding domain and a β-propeller fold. We use a mutagenic screening approach to locate CylK’s active site at its domain interface, identifying two residues, Arg105 and Tyr473, that are required for catalysis. Anomalous diffraction datasets collected with bound bromide ions, a product analog, suggest these residues interact with the alkyl halide electrophile. Additional mutagenesis and molecular dynamics simulations implicates Asp440 and Glu374 in activating the nucleophilic aromatic ring. Bioinformatic analysis of CylK homologs from other cyanobacteria establishes that they conserve these key catalytic amino acids but they are likely associated with divergent reactivity and altered secondary metabolism. By gaining a molecular understanding of this unusual biosynthetic transformation, this work fills a gap in our understanding of how alkyl halides are activated and used by enzymes as biosynthetic intermediates, informing enzyme engineering, catalyst design, and natural product discovery.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guo-Quan Sun ◽  
Wei Zhang ◽  
Li-Li Liao ◽  
Li Li ◽  
Zi-Hao Nie ◽  
...  

AbstractElectrochemical catalytic reductive cross couplings are powerful and sustainable methods to construct C−C bonds by using electron as the clean reductant. However, activated substrates are used in most cases. Herein, we report a general and practical electro-reductive Ni-catalytic system, realizing the electrocatalytic carboxylation of unactivated aryl chlorides and alkyl bromides with CO2. A variety of unactivated aryl bromides, iodides and sulfonates can also undergo such a reaction smoothly. Notably, we also realize the catalytic electrochemical carboxylation of aryl (pseudo)halides with CO2 avoiding the use of sacrificial electrodes. Moreover, this sustainable and economic strategy with electron as the clean reductant features mild conditions, inexpensive catalyst, safe and cheap electrodes, good functional group tolerance and broad substrate scope. Mechanistic investigations indicate that the reaction might proceed via oxidative addition of aryl halides to Ni(0) complex, the reduction of aryl-Ni(II) adduct to the Ni(I) species and following carboxylation with CO2.


2021 ◽  
Author(s):  
Anton A. Gladkov ◽  
Grigory N. Chernov ◽  
Vitalij V. Levin ◽  
Vladimir A. Kokorekin ◽  
Alexander D. Dilman

Synthesis ◽  
2021 ◽  
Author(s):  
Jean-François Paquin ◽  
Xavier Bertrand ◽  
Pascal Paquin ◽  
Laurent Chabaud

AbstractThe hydrochlorination, hydrobromination, and hydroiodination of unactivated alkenes using methanesulfonic acid and inorganic halide salts (CaCl2, LiBr, LiI) in acetic acid are reported. This approach uses readily available and inexpensive reagents to provide the alkyl halides in up to 99% yield. An example of deuteriochlorination using deuterated acetic acid as the solvent is also demonstrated.


2021 ◽  
Vol 11 (6) ◽  
pp. 47-50
Author(s):  
Sachin V Patil

Some new oxime ether derivatives containing benzthiazole heterocyclic nuclei are synthesized. The reaction of 2-mercapto benzthiazole with α-halo ketones followed by reaction with hydroxylamine gave oxime derivatives which on reaction with alkyl halides viz. ethyl chloride, n-propyl chloride, and n-butyl chloride in absolute ethanol afforded the target compounds 4a-l. The structure of all the synthesized compounds was confirmed by spectroscopic methods like mass and NMR. All compounds after structural confirmation were tested for biological activities.


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