Nitrosocarbonyl Carbohydrate Derivatives: Hetero Diels–Alder and Ene Reaction Products for Useful Organic Synthesis

Synthesis ◽  
2020 ◽  
Author(s):  
Paolo Quadrelli ◽  
Marco Corti ◽  
Marco Leusciatti ◽  
Mattia Moiola ◽  
Mariella Mella
Keyword(s):  
Organic Synthesis ◽  
Tertiary Amine ◽  
Diels Alder ◽  
Mild Oxidation ◽  
Reaction Products ◽  
Ene Reaction ◽  
Nitrile Oxides

AbstractThe generation and trapping of two new nitrosocarbonyl intermediates bearing carbohydrate-based chiral substituents is achieved by the mild oxidation of the corresponding nitrile oxides with tertiary amine N-oxides. Their capture with suitable dienes and alkenes afforded the corresponding hetero Diels–Alder cycloadducts and ene adducts from fair to excellent yields. The entire methodology looks highly promising by the easy conversion of aldoximes into hydroxymoyl halides, widening the access to nitrosocarbonyls, versatile tools in organic synthesis.

Biscitraconimides as Anti-Reversion Agents for Diene Rubbers: Spectroscopic Studies on Citraconimide-Squalene Adducts

1997 ◽  
Vol 70 (1) ◽  
pp. 129-145 ◽  
Author(s):  
R. N. Datta ◽  
A. H. M. Schotman ◽  
A. J. M. Weber ◽  
F. G. H. van Wijk ◽  
P. J. C. van Haeren ◽  
...  
Keyword(s):  
Minor Component ◽  
Spectroscopic Studies ◽  
Model System ◽  
Diels Alder ◽  
Main Reaction ◽  
Reaction Products ◽  
Ene Reaction ◽  
Simple Model System ◽  
Conjugated Polyenes ◽  
Diene Rubbers

Abstract The mechanism of anti-reversion activity of biscitraconimides (BCI) during rubber vulcanization has been investigated. Biscitraconimides form crosslinks by reaction with chain modifications which are formed during the reversion process. These additional crosslinks compensate for the sulfidic crosslinks that are lost during the reversion. To allow structural assignments of the adducts formed between rubber and citraconimides, squalene has been used as a simple model system in combination with the currently used additives and sulphur. The products were identified as Diels—Alder adducts of conjugated polyenes, formed during reversion, with citraconimide. The nuclear magnetic resonance (NMR) spectroscopic assignments of the products are discussed. Furthermore the quantification of squalene-BCI adducts via NMR and mass spectrometry (MS) using 13C labelled 1,3-bis (citraconimidomethyl) benzene (BCI-MX) is described. It was found that under the applied conditions (2 h, 170 °C), approximately 80% of the citraconimide groups are converted into squalene-BCI adducts. Diels—Alder adducts are the main reaction products of the reaction. Products from an ene reaction are formed as minor component (less than 20%).

Enantioselective Syntheses of Flavonoid Diels-Alder Natural Products: A Review

2018 ◽  
Vol 15 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Shah Bakhtiar Nasir ◽  
Noorsaadah Abd Rahman ◽  
Chin Fei Chee
Keyword(s):  
Natural Products ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Alder Reaction ◽  
Diels Alder ◽  
Enantioselective Synthesis ◽  
Chiral Ligand ◽  
Asymmetric Syntheses ◽  
Diels Alder Reaction ◽  
Enantioselective Syntheses

Background: The Diels-Alder reaction has been widely utilised in the syntheses of biologically important natural products over the years and continues to greatly impact modern synthetic methodology. Recent discovery of chiral organocatalysts, auxiliaries and ligands in organic synthesis has paved the way for their application in Diels-Alder chemistry with the goal to improve efficiency as well as stereochemistry. Objective: The review focuses on asymmetric syntheses of flavonoid Diels-Alder natural products that utilize chiral ligand-Lewis acid complexes through various illustrative examples. Conclusion: It is clear from the review that a significant amount of research has been done investigating various types of catalysts and chiral ligand-Lewis acid complexes for the enantioselective synthesis of flavonoid Diels-Alder natural products. The results have demonstrated improved yield and enantioselectivity. Much emphasis has been placed on the synthesis but important mechanistic work aimed at understanding the enantioselectivity has also been discussed.

Polar Diels-Alder Reactions Under Microwave Irradiation Employing Different Heterocyclic Compounds as Electrophiles

2019 ◽  
Vol 16 (6) ◽  
pp. 527-543 ◽  
Author(s):  
Pedro M.E. Mancini ◽  
Carla M. Ormachea ◽  
María N. Kneeteman
Keyword(s):  
Organic Synthesis ◽  
Heterocyclic Compounds ◽  
Ionic Conduction ◽  
Theoretical Calculations ◽  
Cycloaddition Reaction ◽  
Diels Alder ◽  
The Other ◽  
Conventional Heating ◽  
Protic Ionic Liquids ◽  
Solvent Free Conditions

During the last twenty years, our research group has been working with aromatic nitrosubstituted compounds acting as electrophiles in Polar Diels-Alder (P-DA) reactions with different dienes of diverse nucleophilicity. In this type of reaction, after the cycloaddition reaction, the nitrated compounds obtained as the [4+2] cycloadducts suffer cis-extrusion with the loss of nitrous acid and a subsequent aromatization. In this form, the reaction results are irreversible. On the other hand, the microwave-assisted controlled heating become a powerful tool in organic synthesis as it makes the reaction mixture undergo heating by a combination of thermal effects, dipolar polarization and ionic conduction. As the Diels-Alder (D-A) reaction is one of the most important process in organic synthesis, the microwave (MW) irradiation was applied instead of conventional heating, and this resulted in better yields and shorter reaction times. Several substituted heterocyclic compounds were used as electrophiles and different dienes as nucleophiles. Two experimental situations are involved: one in the presence of Protic Ionic Liquids (PILs) as solvent and the other under solvent-free conditions. The analysis is based on experimental data and theoretical calculations.

Copper nitrate: a privileged reagent for organic synthesis

2018 ◽  
Vol 16 (15) ◽  
pp. 2602-2618 ◽  
Author(s):  
Mingchun Gao ◽  
Rongxuan Ye ◽  
Weijia Shen ◽  
Bin Xu
Keyword(s):  
Organic Synthesis ◽  
State Of The Art ◽  
Copper Nitrate ◽  
The State ◽  
Nitrile Oxides

This review demonstrates the state-of-the-art applications of copper nitrate as a nitration reagent, oxidant, catalyst, promoter and precursor of nitrile oxides.

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