scholarly journals Synthesis of 1-(1-Arylvinyl)pyridin-2(1H)-ones from Ketones and 2-Fluoropyridine

2021 ◽  
Author(s):  
Takuji Kawamoto ◽  
shunya ikeda ◽  
Akio Kamimura
Keyword(s):  
Biologically Active ◽  
Mechanistic Study ◽  
Efficient Procedure ◽  
Benzene Rings ◽  
Synthetic Intermediates ◽  
Alkylation Reactions ◽  
Vinyl Triflates

Pyridone skeletons are found in numerous biologically active molecules and pharmaceuticals. 1-(1-Arylvinyl)pyridin-2(<i>1H</i>)-ones are synthetic intermediates derived from the enamide moiety, and only few examples of the synthesis of 1-(1-arylvinyl)-2-pyridones have been reported. In this work, a simple and efficient procedure for the synthesis of <i>N</i>-vinyl-substituted pyridones from ketones and 2-fluoropyridine in the presence of trifluoromethane sulfonic anhydride, followed by base treatment is described. Various ketones with electron-donating or -withdrawing groups at the benzene rings can be used in this reaction. A preliminary mechanistic study indicates that it is not very likely that both vinyl triflates and vinyl cations play major roles as intermediates in this transformation. The thus obtained pyridones can be subsequently transformed via C–H arylation and radical alkylation reactions.

scholarly journals Synthesis of 1-(1-Arylvinyl)pyridin-2(1H)-ones from Ketones and 2-Fluoropyridine

2021 ◽  
Author(s):  
Takuji Kawamoto ◽  
shunya ikeda ◽  
Akio Kamimura
Keyword(s):  
Biologically Active ◽  
Mechanistic Study ◽  
Efficient Procedure ◽  
Benzene Rings ◽  
Synthetic Intermediates ◽  
Alkylation Reactions ◽  
Vinyl Triflates

Pyridone skeletons are found in numerous biologically active molecules and pharmaceuticals. 1-(1-Arylvinyl)pyridin-2(<i>1H</i>)-ones are synthetic intermediates derived from the enamide moiety, and only few examples of the synthesis of 1-(1-arylvinyl)-2-pyridones have been reported. In this work, a simple and efficient procedure for the synthesis of <i>N</i>-vinyl-substituted pyridones from ketones and 2-fluoropyridine in the presence of trifluoromethane sulfonic anhydride, followed by base treatment is described. Various ketones with electron-donating or -withdrawing groups at the benzene rings can be used in this reaction. A preliminary mechanistic study indicates that it is not very likely that both vinyl triflates and vinyl cations play major roles as intermediates in this transformation. The thus obtained pyridones can be subsequently transformed via C–H arylation and radical alkylation reactions.

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

Cyclic imines – preparation and application in synthesis

2018 ◽  
Vol 16 (40) ◽  
pp. 7296-7314 ◽  
Author(s):  
Jakub Iwanejko ◽  
Elżbieta Wojaczyńska
Keyword(s):  
Biologically Active Compounds ◽  
Biologically Active ◽  
Active Compounds ◽  
Synthetic Intermediates

Cyclic imines, available from various nitrogen-containing reactants, serve as versatile synthetic intermediates for biologically active compounds.

Hypervalent Iodine-mediated/Catalyzed Oxidative Cycloisomerization/Annulation of Alkynes for Metal-free Synthesis of Oxazoles

2020 ◽  
Vol 24 (18) ◽  
pp. 2048-2069
Author(s):  
Akio Saito
Keyword(s):  
Functional Groups ◽  
Single Step ◽  
Biologically Active ◽  
Hypervalent Iodine ◽  
Sustainable Chemistry ◽  
Metal Free ◽  
Triple Bonds ◽  
Iodine Species ◽  
Low Toxicity ◽  
Synthetic Intermediates

Since oxazoles have found widespread applications not only as synthetic intermediates but also as biologically active compounds, much effort has been focused on developing novel and efficient methods for the synthesis of this heterocycle. From the viewpoint of green and sustainable chemistry, hypervalent iodine and other halogen reagents have gained increasing popularity in metal-free oxidative transformation due to their low toxicity, transition-metal-like reactivity, high stability, easy handling and other benefits. In this account, our two approaches to the metal-free synthesis of oxazoles by means of a peculiar activation of alkynes by iodine species are described with the related contexts. One is iodine(III)-mediated/catalyzed oxidative cycloisomerization reactions of N-propargyl amides for the preparation of oxazoles bearing various functional groups at their side chains. In these reactions, iodine(III) species works as a donor of various heteroatomic functional groups as well as an activator of carbon-carbon triple bonds in a single step. Furthermore, this methodology can be extended to iodine(III)-mediated/catalyzed oxidative annulation of alkynes and nitriles as another approach, in which heteroatoms on iodine(III) species are incorporated in the azole rings.

The Hydrosilylation and Cyanosilylation of Ketones Catalyzed using Metal Borohydrides

2019 ◽  
Vol 16 (2) ◽  
pp. 276-282 ◽  
Author(s):  
Yu Liu ◽  
Duodong Zhang ◽  
Yangyang Ma ◽  
Jiayun Li ◽  
Ying Bai ◽  
...  
Keyword(s):  
Carbonyl Compounds ◽  
Reaction Rate ◽  
Biologically Active ◽  
High Conversion ◽  
Similar Reaction ◽  
Reaction Conditions ◽  
Efficient Procedure ◽  
Hydrosilylation Reaction ◽  
One Step ◽  
Relative Catalytic Activity

Aim and Objective: The hydrosilylation reaction of carbonyl compounds has emerged as a powerful method in organic synthesis. The catalytic hydrosilylation of ketones is a valuable transformation because it generates protected cyanosilylation reaction of carbonyl compounds is an efficient procedure for the synthesis of silylated cyanohydrins, which are readily converted into useful functionalized compounds, such as cyanohydrins, α-hydroxy acids, β-amino alcohols and other biologically active compounds. Materials and Methods: A facile, economic and efficient method has been developed for the hydrosilylation and cyanosilylation of ketones using metal borohydrides. A series of silylated ethers and silylated cyanohydrins can be isolated via direct distillation. Results: The catalytic properties of a range of metal borohydrides in the hydrosilylation reaction of acetophenone with diphenylsilane were investigated. The relative catalytic activity of the borohydride catalyst studied was as follows: (CH3)4NBH4> (PhCH2)(CH3)3NBH4> (CH2CH3)4NBH4> (CH3CH2CH2CH3)4NBH4> NaBH4> KBH4> LiBH4. The cyanosilylation of acetophenone using trimethylsilyl cyanide (TMSCN) in the presence of NaBH4 occurred under similar reaction conditions. An excellent reaction rate and high conversion were obtained. Conclusion: The metal borohydride-catalyzed hydrosilylation alcohols in one step. The and cyanosilylation of ketones could be carried out smoothly under mild reaction conditions. Among the metal borohydrides studied, an excellent reaction rate and high conversion were obtained using NaBH4, NaBH (CH2CH3)3 or (alkyl)4 NBH4 as the reaction catalyst.

New Hydrophobicity Constants of Substituents in Pyrazine Rings Derived from RP-HPLC Study

2008 ◽  
Vol 73 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Marta Kučerová-Chlupáčová ◽  
Veronika Opletalová ◽  
Josef Jampílek ◽  
Jan Doležel ◽  
Jiří Dohnal ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Heterocyclic Compounds ◽  
Biological Activities ◽  
Biologically Active ◽  
Grignard Reaction ◽  
Rp Hplc ◽  
Wide Range ◽  
Benzene Rings ◽  
Homolytic Alkylation ◽  
Hplc Study

Pyrazine derivatives show a wide range of biological activities. 1-Pyrazin-2-ylethan-1-ones have served as food flavourants, and together with pyrazine-2-carbonitriles have been widely used as intermediates in the synthesis of various heterocyclic compounds. In our laboratory, substituted pyrazine-2-carbonitriles and 1-pyrazin-2-ylethan-1-ones have been used as intermediates for the preparation of potential antifungal and antimycobacterial drugs. Using established methods, a library of pyrazine derivatives was synthesized. Homolytic alkylation of commercially available pyrazine-2-carbonitrile yielded a series of 5-alkylpyrazine-2-carbonitriles which were converted into the corresponding 1-(5-alkylpyrazin-2-yl)ethan-1-ones (5-alkyl-2-acetylpyrazines) via the Grignard reaction. Homolytic acetylation of pyrazine-2-carbonitrile yielded 5-acetylpyrazine-2-carbonitrile. Using the same procedure, 3-acetyl-5-tert-butylpyrazine-2-carbonitrile was obtained with 5-tert-butylpyrazine-2-carbonitrile as a starting material. The hydrophobicity of the compounds was determined both experimentally (RP-HPLC) and by computation (CS ChemOffice Ultra version 9.0, ACD/LogP version 1.0 and ACD/LogP version 9.04), and both the approaches were compared. New hydrophobicity constants π based on experimental results were derived. These constants are markedly different from tabulated constants π valid for benzene rings, and can be widely used in estimating physicochemical properties of new biologically active pyrazines.

Asymmetric Rhodium-Catalyzed Allylic Substitution Reactions with Nitrile-Stabilized Carbanions

Synlett ◽  
2021 ◽  
Author(s):  
Mai-Jan Tom ◽  
P. Andrew Evans
Keyword(s):  
Biologically Active ◽  
Allylic Alkylation ◽  
Substitution Reactions ◽  
Stereogenic Centers ◽  
Enantioselective Reactions ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Alkylation Reactions ◽  
Quaternary Stereogenic Centers ◽  
Selective Access

This Account summarizes our recent work on rhodium-catalyzed allylic alkylation reactions with nitrile-stabilized carbanions. Despite the challenges associated with employing nitrile stabilized nucleophiles in transition-metal-catalyzed reactions, we recently developed both enantiospecific and enantioselective allylic alkylation reactions. Notably, these novel reactions permit the expedient and selective access to an array of acyclic ternary and quaternary stereogenic centers that are present in important biologically active molecules. 1 Introduction 2 Enantiospecific Reactions of Nitrile-Stabilized Anions 3 Enantioselective Reactions of Nitrile-Stabilized Anions 4 Conclusion

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