scholarly journals Organofluorosilicates in Organic Synthesis. XVI. Synthesis of Organopentafluorosilicatesviathe Diels-Alder, Ene, and Friedel-Crafts Reaction. Their Transformations to Organic Halides and Alcohols

1982 ◽  
Vol 55 (1) ◽  
pp. 255-260 ◽  
Author(s):  
Kohei Tamao ◽  
Jun-ichi Yoshida ◽  
Munetaka Akita ◽  
Yoshihiro Sugihara ◽  
Takahisa Iwahara ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Diels Alder ◽  
Organic Halides

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.

Complex Reactions

2001 ◽  
Author(s):  
L. K. Doraiswamy
Keyword(s):  
Organic Synthesis ◽  
Product Distribution ◽  
Diels Alder ◽  
Point Of View ◽  
Complex Reaction ◽  
Design Point ◽  
Multiple Reactions ◽  
Practical Strategy ◽  
Multistep Reactions ◽  
Quantitative Treatment

When a reactant or a set of reactants undergoes several reactions (at least two) simultaneously, the reaction is said to be a complex reaction. The total conversion of the key reactant, which is used as a measure of reaction in simple reactions, has little meaning in complex reactions, and what is of primary interest is the fraction of reactant converted to the desired product. Thus the more pertinent quantity is product distribution from which the conversion to the desired product can be calculated. This is usually expressed in terms of the yield or selectivity of the reaction with respect to the desired product. From the design point of view, an equally important consideration is the analysis and quantitative treatment of complex reactions, a common example of which is the dehydration of alcohol represented by We call such a set of simultaneous reactions a complex multiple reaction. It is also important to note that many organic syntheses involve a number of steps, each carried out under different conditions (and sometimes in different reactors), leading to what we designate as multistep reactions (normally called a synthetic scheme by organic chemists). This could, for example, be a sequence of reactions like dehydration, oxidation, Diels-Alder, and hydrogenation. This chapter outlines simple procedures for the treatment of complex multiple and multistep reactions and explains the concepts of selectivity and yield. For a more detailed treatment of multiple reactions, the following books may be consulted: Aris (1969) and Nauman (1987). We conclude the chapter by considering a reaction with both catalytic and noncatalytic steps, which also constitutes a kind of complex reaction. Because both chemists and chemical engineers are involved in formulating a practical strategy for accomplishing an organic synthesis, it is important to appreciate the roles of each.

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.

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