Palladium-Catalyzed Synthesis of Aryl and Heteroaryl Difluoromethylated Phosphonates

Synthesis ◽  
2017 ◽  
Vol 50 (04) ◽  
pp. 778-784 ◽  
Author(s):  
Thomas Poisson ◽  
Maria Ivanova ◽  
Tatiana Besset ◽  
Xavier Pannecoucke
Keyword(s):  
Important Class ◽  
Mild Conditions ◽  
Palladium Catalyzed

We report the palladium-catalyzed introduction of the di­fluoromethylposphonate unit onto aryl and heteroaryl iodides under mild conditions. Using the CuCF2PO(OEt)2 species generated in situ, the method allows the functionalization of various otherwise reluctant substrates. In addition, this reaction permits the formation of CF2PO(OEt)2-containing heterocycles, an important class of compounds. This process broadens the current toolbox of methods available to construct CF2PO(OEt)2-containing molecules.

scholarly journals Chemoselective activation of amide carbonyls towards nucleophilic reagents

2016 ◽  
Author(s):  
Bartłomiej Furman
Keyword(s):  
Chemical Biology ◽  
Grignard Reagents ◽  
Synthetic Method ◽  
Important Class ◽  
Selective Activation ◽  
One Pot ◽  
Mild Conditions ◽  
Nucleophilic Reagents ◽  
Danishefsky's Diene

Amides represent an important class of compounds in chemistry, chemical biology and pharmaceutical industry. Their broad utility in many fields is closely tied to the structure of the amide moiety which endows these compounds with unique features. The low reactivity of amide carbonyls towards nucleophiles is a major obstacle to their further functionalization. Selective activation of amides and lactams enables access to novel reactivity pathways and opens up intriguing perspectives in synthesis. Recently, we have demonstrated that upon treatment with Cp2Zr(H)Cl (Schwartz’s reagent), five- and six-membered lactams, including sugar- and hydroxy acid-derived lactams, can be easily converted into imines under mild conditions. In addition, as was also shown, in situ generated cyclic imines can be directly subjected to further reactions with nucleophilic reagents such as allyltributylstannane, Grignard reagents, enolates or Danishefsky’s diene to afford α-functionalized pyrrolidines, piperidines and polyhydroxylated pyrrolidine peptidomimetic scaffolds in a one-pot manner. The key advantage of the presented approach is the simplicity and convenience of generation of sugar-derived imines from readily available starting materials: sugar-derived lactams. The use of sugar-derived lactams as cyclic imine precursors is crucial to the efficiency of the described synthetic method. These compounds are more readily prepared, handled, and stored than the alternative precursors of cyclic imines such as nitrones, N-chloroamines or azido aldehydes. In the second part of the lecture a method for preparing 2,3-disubstituted indoles from commercially available isatins will be briefly presented.

scholarly journals Chemoselective activation of amide carbonyls towards nucleophilic reagents

2016 ◽  
Author(s):  
Bartłomiej Furman
Keyword(s):  
Chemical Biology ◽  
Grignard Reagents ◽  
Synthetic Method ◽  
Important Class ◽  
Selective Activation ◽  
One Pot ◽  
Mild Conditions ◽  
Nucleophilic Reagents ◽  
Danishefsky's Diene

Amides represent an important class of compounds in chemistry, chemical biology and pharmaceutical industry. Their broad utility in many fields is closely tied to the structure of the amide moiety which endows these compounds with unique features. The low reactivity of amide carbonyls towards nucleophiles is a major obstacle to their further functionalization. Selective activation of amides and lactams enables access to novel reactivity pathways and opens up intriguing perspectives in synthesis. Recently, we have demonstrated that upon treatment with Cp2Zr(H)Cl (Schwartz’s reagent), five- and six-membered lactams, including sugar- and hydroxy acid-derived lactams, can be easily converted into imines under mild conditions. In addition, as was also shown, in situ generated cyclic imines can be directly subjected to further reactions with nucleophilic reagents such as allyltributylstannane, Grignard reagents, enolates or Danishefsky’s diene to afford α-functionalized pyrrolidines, piperidines and polyhydroxylated pyrrolidine peptidomimetic scaffolds in a one-pot manner. The key advantage of the presented approach is the simplicity and convenience of generation of sugar-derived imines from readily available starting materials: sugar-derived lactams. The use of sugar-derived lactams as cyclic imine precursors is crucial to the efficiency of the described synthetic method. These compounds are more readily prepared, handled, and stored than the alternative precursors of cyclic imines such as nitrones, N-chloroamines or azido aldehydes. In the second part of the lecture a method for preparing 2,3-disubstituted indoles from commercially available isatins will be briefly presented.

scholarly journals Chemoselective activation of amide carbonyls towards nucleophilic reagents

2016 ◽  
Author(s):  
Bartłomiej Furman
Keyword(s):  
Chemical Biology ◽  
Grignard Reagents ◽  
Synthetic Method ◽  
Important Class ◽  
Selective Activation ◽  
One Pot ◽  
Mild Conditions ◽  
Nucleophilic Reagents ◽  
Danishefsky's Diene

Amides represent an important class of compounds in chemistry, chemical biology and pharmaceutical industry. Their broad utility in many fields is closely tied to the structure of the amide moiety which endows these compounds with unique features. The low reactivity of amide carbonyls towards nucleophiles is a major obstacle to their further functionalization. Selective activation of amides and lactams enables access to novel reactivity pathways and opens up intriguing perspectives in synthesis. Recently, we have demonstrated that upon treatment with Cp2Zr(H)Cl (Schwartz’s reagent), five- and six-membered lactams, including sugar- and hydroxy acid-derived lactams, can be easily converted into imines under mild conditions. In addition, as was also shown, in situ generated cyclic imines can be directly subjected to further reactions with nucleophilic reagents such as allyltributylstannane, Grignard reagents, enolates or Danishefsky’s diene to afford α-functionalized pyrrolidines, piperidines and polyhydroxylated pyrrolidine peptidomimetic scaffolds in a one-pot manner. The key advantage of the presented approach is the simplicity and convenience of generation of sugar-derived imines from readily available starting materials: sugar-derived lactams. The use of sugar-derived lactams as cyclic imine precursors is crucial to the efficiency of the described synthetic method. These compounds are more readily prepared, handled, and stored than the alternative precursors of cyclic imines such as nitrones, N-chloroamines or azido aldehydes. In the second part of the lecture a method for preparing 2,3-disubstituted indoles from commercially available isatins will be briefly presented.

Diastereoselective Palladium-Catalyzed [4+1] Cycloadditions of Vinyl Benzoxazinanones with in situ Formed Carbenes

Synthesis ◽  
2021 ◽  
Author(s):  
Yanhua Ma ◽  
Fanxiao Meng ◽  
Ruonan Wang ◽  
Yaxin Fan ◽  
Qinqiang Su ◽  
...  
Keyword(s):  
Functional Group ◽  
Quinone Methides ◽  
Nucleophilic Carbenes ◽  
Mild Conditions ◽  
Palladium Catalyzed

Herein, we present a palladium-catalyzed tandem [4+1] cycloadditions of vinyl benzoxazinanones with N-tosylhydrazones. The cycloaddition is accomplished by merging the in situ generated aza-ortho-quinone methides (aza-o-QMs) with nucleophilic carbenes. This method enables the construction of diverse indolines with broad functional group compatibility in good yields with high levels of diastereoselectivity under mild conditions.

scholarly journals The Fluoride Anion-Catalyzed Sulfurization of Thioketones with Elemental Sulfur Leading to Sulfur-Rich Heterocycles: First Sulfurization of Thiochalcones

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 822
Author(s):  
Grzegorz Mlostoń ◽  
Jakub Wręczycki ◽  
Katarzyna Urbaniak ◽  
Dariusz M. Bieliński ◽  
Heinz Heimgartner
Keyword(s):  
Elemental Sulfur ◽  
Fluoride Anion ◽  
Ring Size ◽  
Mild Conditions ◽  
Tetrabutylammonium Fluoride ◽  
Cesium Fluoride ◽  
Secondary Reactions ◽  
Derivatives Of

Fluoride anion was demonstrated as a superior activator of elemental sulfur (S8) to perform sulfurization of thioketones leading to diverse sulfur-rich heterocycles. Due to solubility problems, reactions must be carried out either in THF using tetrabutylammonium fluoride (TBAF) or in DMF using cesium fluoride (CsF), respectively. The reactive sulfurizing reagents are in situ generated, nucleophilic fluoropolysulfide anions FS(8−x)−, which react with the C=S bond according to the carbophilic addition mode. Dithiiranes formed thereby, existing in an equilibrium with the ring-opened form (diradicals/zwitterions) are key-intermediates, which undergo either a step-wise dimerization to afford 1,2,4,5-tetrathianes or an intramolecular insertion, leading in the case of thioxo derivatives of 2,2,4,4-tetramethylcyclobutane-1,3-dione to ring enlarged products. In reactions catalyzed by TBAF, water bounded to fluoride anion via H-bridges and forming thereby its stable hydrates is involved in secondary reactions leading, e.g., in the case of 2,2,4,4-tetramethyl-3-thioxocyclobutanone to the formation of some unexpected products such as the ring enlarged dithiolactone and ring-opened dithiocarboxylate. In contrast to thioketones, the fluoride anion catalyzed sulfurization of their α,β-unsaturated analogues, i.e., thiochalcones is slow and inefficient. However, an alternative protocol with triphenylphosphine (PPh3) applied as a catalyst, offers an attractive approach to the synthesis of 3H-1,2-dithioles via 1,5-dipolar electrocyclization of the in situ-generated α,β-unsaturated thiocabonyl S-sulfides. All reactions occur under mild conditions and can be considered as attractive methods for the preparation of sulfur rich heterocycles with diverse ring-size.

A new approach to arylhydrazides via the reaction of the Mitsunobu reagent with arynes: further application to access diverse nitrogen-containing heterocycles in one pot

2017 ◽  
Vol 4 (8) ◽  
pp. 1636-1639 ◽  
Author(s):  
Bin Cheng ◽  
Bian Bao ◽  
Yanhe Chen ◽  
Ning Wang ◽  
Yun Li ◽  
...  
Keyword(s):  
One Pot ◽  
New Approach ◽  
Mild Conditions ◽  
Highly Active ◽  
Active Intermediates

A new route to arylhydrazides involving the reaction of two highly active intermediates, the 1,3-zwitterion generated in situ from the Mitsunobu reagent and arynes, under mild conditions has been developed.

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