Regioselective Amination or Alkoxylation of Halogenated Amino-, Thio- or Alkoxypyridines via Pyridyne Intermediates

Synthesis ◽  
2021 ◽  
Author(s):  
Paul Knochel ◽  
Benjamin Heinz ◽  
Dimitrije Djukanovic ◽  
Fiona Siemens ◽  
Mohamed Idriess ◽  
...  
Keyword(s):  
Substitution Reactions

AbstractThe treatment of 3-halopyridines (Cl, Br) bearing an R-substituent in position 2 (R = OEt, NEt2, N-piperidyl, or SEt) or in position 5 (R = OMe, OEt, SEt, NMe2, NEt2, or aryl) with KHMDS and an amine at 25 °C for 12 hours in THF provided regioselectively 3- and 4-aminated pyridines in 56–90% yields. The reaction of 3-bromo-2-diethylaminopyridine with various alcohols in the presence of t-BuOK/18-crown-6 in THF at 80 °C for 20–60 hours gave various 4-alkoxy-2-diethylaminopyridines in 61–81% yields. These substitution reactions were proposed to proceed via pyridyne intermediates.

Spatiotemporal Control of Amide Radicals During Photocatalysis

2020 ◽  
Author(s):  
Shogo Mori ◽  
Takahiro Aoki ◽  
Kaliyamoorthy Selvam ◽  
Shunichi Fukuzumi ◽  
Jieun Jung ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Nickel Complex ◽  
Nickel Complexes ◽  
Semiconductor Material ◽  
Radical Reactions ◽  
Substitution Reactions ◽  
Carbon Neutrality ◽  
Spatiotemporal Control ◽  
Scalable Production ◽  
Salt Waste

Despite the continuing popularity of radical reactions in organic synthesis, much remains to be explored in this area. Herein, we describe how spatiotemporal control can be exerted over the formation and reactivity of divergent exchangeable formamide radicals using nickel complexes with a semiconductor material (TiO<sub>2</sub>) under irradiation from near-UV–Vis light. Depending on the bipyridine ligand used and the quantity of the nickel complex that is hybridized on or nonhydridized over the TiO<sub>2</sub> surface, these radicals selectively undergo substitution reactions at the carbon center of carbon–bromine bonds that proceed via three different pathways. As the scalable production of formamides from CO<sub>2</sub> does not produce salt waste, these methods could add a new dimension to the search for carbon neutrality through the indirect incorporation of CO<sub>2</sub> into organic frameworks.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

The Chemistry of Triazine Isomers: Structures, Reactions, Synthesis and Applications

2020 ◽  
Vol 20 ◽  
Author(s):  
Neelottama Kushwaha ◽  
C S Sharma
Keyword(s):  
Basic Property ◽  
Electrophilic Substitution ◽  
Antimicrobial Agents ◽  
Resonance Energy ◽  
Heterocyclic Ring ◽  
Ring System ◽  
Agricultural Fields ◽  
Substitution Reactions ◽  
Anti Cancer ◽  
Benzene Structure

: Triazine is the six-membered heterocyclic ring containing three nitrogen which replaces carbon-hydrogen unit in the benzene ring. Based on nitrogen position present in the ring system, it is categorized in three isomeric forms i.e.1, 2, 3-triazine (vicinal triazine), 1, 2, 4-triazine (asymmetrical triazine or isotriazine) and 1, 3, 5-triazine (symmetrical or s-triazine or cyanidine). Triazines have weakly basic property. Its isomers have much weaker resonance energy than benzene structure, so nucleophilic substitution reactions are more preferred than electrophilic substitution reactions. Triazine isomers and their derivatives are known to play important roles possessing various activities in medicinal and agricultural fields such as anti-cancer, antiviral, fungicidal, insecticidal, bactericidal, herbicidal, antimalarial and antimicrobial agents.

Synthesis and Evaluation of Antioxidant, Antimicrobial and Anticancer Properties of 2-(Prop-2-yn-1-yloxy)benzaldehyde Derivatives

2019 ◽  
Vol 16 (5) ◽  
pp. 415-423
Author(s):  
Metin Konus ◽  
Selahattin Aydemir ◽  
Can Yilmaz ◽  
Arif Kivrak ◽  
Aslihan Kurt Kizildogan ◽  
...  
Keyword(s):  
Antioxidant Capacity ◽  
Breast Adenocarcinoma ◽  
Substitution Reactions ◽  
Anticancer Properties ◽  
Microdilution Method ◽  
Agar Disc ◽  
Broth Microdilution Method ◽  
Total Antioxidant ◽  
Benzaldehyde Derivatives ◽  
High Antifungal Activity

5-bromo-2-(prop-2-yn-1-yloxy)benzaldehyde (compound 3) and 3,5-di-tert-butyl-2-(prop-2- yn-1-yloxy)benzaldehyde (compound 5) were synthesized via nucleophilic substitution reactions. Compound 5 showed higher antioxidant capacity with respect to compound 3 in all the four different antioxidant activity methods used. Moreover, in phosphomolybdenum assay, compound 5, with 1.1 proportion value, showed almost the same total antioxidant capacity compared to universal trolox standard. Furthermore, Broth microdilution method and agar disc diffusion tests demonstrated that the same compound also exhibited good antibacterial activity towards the bacteria Bacillus subtilis. Finally, both of the benzaldehyde compounds showed high antifungal activity against Aspergillus niger. In this study, compound 5 (IC50: 54.3 µg/ml) showed significant cytotoxic activity against breast adenocarcinoma cell line MCF-7 with respect to compound 3 (IC50: 173.4 µg/ml).

Intermolecular hydrogen transfer in unsaturated hydrocarbons induced by dimeric titanocene

1983 ◽  
Vol 48 (10) ◽  
pp. 2924-2936 ◽  
Author(s):  
Karel Mach ◽  
Lidmila Petrusová ◽  
Helena Antropiusová ◽  
Vladimír Hanuš ◽  
František Tureček ◽  
...  
Keyword(s):  
Hydrogen Transfer ◽  
Titanium Content ◽  
Esr Spectra ◽  
Stable Complex ◽  
Catalytic Complex ◽  
Substitution Reactions ◽  
Unsaturated Hydrocarbons ◽  
Linear Alkanes ◽  
Saturated And Aromatic Hydrocarbons ◽  
Intermolecular Hydrogen Transfer

μ-(η5 : η5-Fulvalene)-di-μ-hydrido-bis(η5-cyclopentadienyltitanium) and μ-(η5 : η5-fulvalene)-μ-chloro-μ-hydrido-bis(cyclopentadienyltitanium) form a thermally stable complex which catalyzes the intermolecular hydrogen transfer in unsaturated hydrocarbons, in addition to isomerizations and cyclizations. Cyclic hydrocarbons disproportionate under catalysis to saturated and aromatic hydrocarbons, while linear olefins yield predominantly linear alkanes and high molecular weight tar. The catalyst enables the hydrocarbon system to approach the thermodynamic equilibrium through a series of substitution reactions between alkyl- and allyltitanocene-like species and olefins and dienes. The catalytic complex was characterized by UV and ESR spectra. About one half of overall titanium content could be converted to mononuclear η3-allyltitanocene-like species, stable up to 400 °C. This exceptional thermal stability is ascribed to a firmly bound allyl containing ligand.

Fluorinated tricyclic neuroleptics with prolonged action: 8-Methoxy, 8-ethoxy, 8-ethylthio and 8-hydroxy derivatives of 3-fluoro-10-(4-methylpiperazino)-10,11-dihydrodibenzo[b,f]thiepin

1982 ◽  
Vol 47 (5) ◽  
pp. 1382-1391 ◽  
Author(s):  
Jiří Jílek ◽  
Josef Pomykáček ◽  
Jiřina Metyšová ◽  
Miroslav Protiva
Keyword(s):  
Acetic Acid ◽  
Polyphosphoric Acid ◽  
Prolonged Action ◽  
Substitution Reactions ◽  
Methoxy Derivative ◽  
Chloro Derivatives ◽  
Boron Tribromide ◽  
Derivatives Of ◽  
Central Depressant ◽  
Boiling Toluene

Acids IIa-c were prepared by reactions of (4-fluoro-2-iodophenyl)acetic acid with 4-methoxythiophenol, 4-ethoxythiophenol and 4-(ethylthio)thiophenol and cyclized with polyphosphoric acid in boiling toluene to dibenzo[b,f]thiepin-10(11H)-ones IIIa-c. Reduction with sodium borohydride afforded the alcohols IVa-c which were treated with hydrogen chloride and gave the chloro derivatives Va-c. Substitution reactions with 1-methylpiperazine resulted in the title compounds Ia-c out of which the methoxy derivative Ia was transformed by demethylation with boron tribromide to the phenol Id. Compounds Ia-d are very potent neuroleptics exhibiting a clear prolongation of the central depressant and some prolongation of the cataleptic activity.

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