Extraordinary mechanism of the diels alder reaction. In a cycloaddition reaction, a 1,3diene reacts with an alkene, or dienophile, to produce a sixmembered ring. New synthetic applications of the dielsalder reaction. Dielsalder reaction synthesis of cisnorbornene2,3endodicarboxylic anhydride introduction in 1921, otto diels and kurt alder discovered that certain alkenes and alkynes can undergo a 1,4addition with conjugated dienes to give substituted cyclohexenes or 1,4. That addition reaction generally produces two diasteroisomers endo and exo. At the end of the article, we provide a set of tools that may facilitate the application of the dielsalder reaction to solve important pharmaceutical or biomedical problems. The formation and the proportion of the isomers depend on several conditions such as the solvent, temperature, and catalyst 1,2. Diels alder reactions are concerted, stereospecific, and follow the endo rule. Timothy swager condensed the lectures into 2 sessions. Preparation of cisnorbornene2,3endodicarboxylic anhydride introduction.
Also think in general terms of whether or not the reactions are reversible, what is lost during the reaction, how many steps are typically involved, the conformational requirement for the diene andor dienophile, etc. The general reaction and mechanism is depicted in figure 1. The dielsalder reaction dar is one of the most useful reactions in organic synthesis. The dielsalder reaction is one in which a conjugated diene bonds in with an alkene to produce a cyclohexene molecule. The development and application of powerful cascade dielsalder strategies for natural product synthesis are explored in chapters four, five and six. The driving force of the reaction is the formation of new. Introduction the dielsalder reaction dar is one of the most useful reactions in organic synthesis. Anthracene 1 will serve as a studentfriendly lowsmell diels alder diene, with the labeled carbons functioning as the reactive diene. The purpose of this experiment was to demonstrate the formation of sixmembered rings by cycloaddition, also known as a dielsalder reaction. Intramolecular dielsalder reactions rebecca wilson macmillan group meeting january 24, 2001 i. As always, ask where organic waste containers are located in the lab. Ch3 o ph h3c h3c o o o i obn ho bno ch3 h3c o h3c o alcl3 bno o or o or o ro et2alcl ch3 ch3 ch3 ibu2alcl ibu2alcl et2alcl alcl3 o o o h3c o ch3 ch3 ch3 h3c ch3 co2r co2r myers asymmetric diels. In this lab we reacted anthracene with maleic anhydride to get 9,10dihydroanthracene9,10. Reaction of maleic anhydride with anthracene introduction.
The process by which the reaction occurs is by cycloaddition. Introduction the dielsalder reaction is a onestep reaction of a conjugated diene and a dienophile, which is reversible. The woodwardhoffmann reaction not only represents the prototype of cycloadditions but the whole class of pericyclic reactions. A brief introduction to the diels alder reaction youtube. Moreover, all of the atoms that are participating in the reaction form bonds simultaneously. The dielsalder cycloaddition dacreaction is a commonly employed reaction for the formation of cc bonds. Background conjugated dienes can react with alkenes via a 1,4cycloaddition reaction, a dielsalder reaction. Dac catalysis can be achieved by using lewis acids and via reactant confinement in. These authors noticed, for the first time, a beneficial rate effect of water on the dielsalder reaction. Anthracene acts as the diene and has low reactivity, while maleic anhydride. Thermodynamic and kinetic study of dielsalder reaction. Advanced organic diels alder reaction the cube method is a nice way to visualise the relative stereochemistry finally, remember that the dienophile invariably reacts from the less hindered face if you are a little rusty on the dielsalder reaction either reread your lecture notes or any standard organic text book 3 draw a cube add the. Alder da reaction is one of the most applied and best investigated synthetic methods in chemistry1. It is the prototypical example of a pericyclic reaction with a concerted mechanism.
Introduction and purpose a dielsalder reaction of 1,3butadiene and aleic anhydride will be carried out to produce cyclohexenecis1,2dicarboxylic anhydride. In 1921, otto diels and kurt alder discovered that certain alkenes and alkynes can undergo a 1,4addition with conjugated dienes to give substituted cyclohexenes or 1,4cyclohexadienes. The dielsalder reaction is one of the most powerful tools used in. In order to improve the yield and to avoid the reversibility of the reaction, homogeneous lewis acids 14, solid acids 56 as catalyst, high pressures 68 andor water as a solvent 910 have been reported. This reaction provides an opportunity to surpass the limitations related to the coupling of chemically sensitive biomolecules as antibodies, especially in aqueous. The representative of all dielsalder reactions as well as its most elementary one is the reaction between 1,3butadiene and ethylene. In a typical dielsalder reaction the dienophiles that are most. This type of reaction is named in honor of the german scientists, otto diels and kurt alder, who.
Introduction in the dielsalder reaction, a 1,3 diene reacts with a dienophile to form a six membered ring adduct. Bulletin of the chemical society of japan 1987, 60 11, 41904192. Background conjugated dienes can react with alkenes via a 1,4cycloaddition reaction, a diels alder reaction. Diels alder reaction lab 3 the diels alder reaction.
Today well introduce a reaction i consider to be the most useful and powerful reaction in all of organic. Pdf introduction to diels alder reaction, its mechanism. New methods of controlling the stereochemical outcome of the dielsalder reaction are presented in chapters two and three. It is the authors responsibility to use the introduction to. Diels alder reactions of allene with benzene and butadiene. Pdf understanding the mechanism of polar dielsalder reactions. In particular, and among the most interesting environmentalfriendly.
A general introduction to the dielsalder reaction is presented, along with a discussion of potential pitfalls and challenges. The dielsalder reaction, named after the german chemists who developed it, is a method for producing simple ring compounds. The purpose of this experiment is to carry out a dielsalder reaction of 1,3butadiene and maleic anhydride to produce 4cyclohexenecis1,2dicarboxylic anhydride. The dielsalder reaction is a useful tool for generating functionalized chiral molecules through the concerted cycloaddition of dienes and dienophiles leading to sixmembered rings. Among other methods introduced to achieve excellent regioselectivity, as well as to incorporate useful functional groups, danishefsky. Industrial applications of the dielsalder reaction. The reaction is the 1,4addition of an electrophile and a nucleophile to a conjugated diene.
In this update on the dielsalder reaction we would like to present an overview on. Both the anhydride and the diacid will be tested via unsaturation tests and melting point determination. Dielsalder reactions are concerted, stereospecific, and follow the endo rule. In order to improve the yield and to avoid the reversibility of the reaction, homogeneous lewis acids 14, solid acids 5,6 as catalyst, high pressures 68.
The regiochemistry of the dielsalder reaction is determined by the position of the electron donating groups of the diene, and is fully understood by molecular orbital theory. Anthracene 1 will serve as a studentfriendly lowsmell dielsalder diene, with the labeled carbons functioning as the reactive diene. Diels alder reaction, intramolecular, transannular. Diels alder reaction an overview sciencedirect topics. Volume 35, issue 16, 18 april 1994, pages 25452548. In organic chemistry, the dielsalder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile also spelled dieneophile, to form a substituted cyclohexene derivative. It may be easier to explain by simply looking at the resonance structures of the diene and dienophile. Diels alder 1 mechanism and regiochemistry duration. Introduction to diels alder reaction, its mechanism and recent advantages. Asymmetric dielsalder reaction of acrylamides having trans 2,5disubstituted pyrrolidines as chiral auxiliaries. Diels alder reaction is the reaction of a diene with a species capable of reacting with the diene, the dienophile a diene is a hydrocarbon that contains two carbon double bonds, while a dienophile is an electrondeficient alkene. As aforementioned the dielsalder reaction forms a cyclohexene ring. In organic chemistry, the dielsalder reaction is a chemical reaction between a conjugated.
Most dielsalder reactions occur with normal electron demand in which an electronrich nucleophilic diene reacts with an electronpoor electrophilic dienophile. Proper lab gogglesglasses must be worn even over prescription glasses. Enantioselective catalysis h r r r r r r r r h h r r introduction. A diels alder was used to form a new carbon carbon double bond using a diene and a dienophile. Xylene dimethylbenzene is used as a highboiling solvent so that the reaction will work fast enough to complete conveniently. Alder reaction based on a 11phase mechanism obtained by the urva analysis. Diels alder reaction is the reaction of a diene with a species capable of reacting with the diene, the dienophile. Besides the grignard reaction, it is the most cited name reaction in chemical literature. The dienophile undergoes dielsalder reaction with a diene introducing such a functionality onto the product molecule. Cyclopentadiene and maleic anhydride were reacted together to form cisnorbornene5,6endodicarboxylic anhydride. Here you will find a brief introduction to the dielsalder reaction.
Diiodosamarium, a catalyst precursor for dielsalder and. Dielsalder reaction of cyclopentadiene with maleic anhydride. The dielsalder reaction dienophiles 8 there is a strong electronic substituent effect on the dielsalder reaction. Diiodosamarium, a catalyst precursor for diels alder and hetero diels alder reactions. Pdf dual activation of aromatic dielsalder reactions. Pdf introduction to diels alder reaction, its mechanism and. The study of dielsalder reaction kinetics is extensively. Also, in two patents the dielsalder reaction is mentioned in connection with water 4. Maleic anhydride 2 will function as the dienophile. Advanced organic dielsalder reaction the cube method is a nice way to visualise the relative stereochemistry finally, remember that the dienophile invariably reacts from the less hindered face if you are a little rusty on the dielsalder reaction either reread your lecture notes or any standard organic text book 3 draw a cube add the. A reaction of a conjugated diene purpose to perform a reaction of a diene with a dienophile, to perform a microscale recrystallization of the product, and to gain experience using the ir spectrometer.
The diene was the molecule of the reaction that had 4. This product was formed by the use of a dielsalder reaction between anthracene and maleic anhydride. A diene is a hydrocarbon that contains two carbon double bonds, while a dienophile is an electrondeficient alkene. In the dielsalder reaction, a conjugated diene reacts with a dienophile. Alder adduct of the unsubstituted 3methylenevinylcyclobutane was found in previous computational studies by houk and coworkers to occur in stepwise fashion. Dielsalder reaction of cyclopentadiene with maleic anhydride johnson, chad philip. This means that the electrons are transferred in a cyclic fashion between the diene and the alkene to for the cyclic structure. Unconventional exo selectivity in thermal normalelectron. Introduction the purpose of this weeks lab was to react anthracene and maleic anhydride in a diels alder reaction to form 9,10dihydro9,10ethanoanthraccene11,12dicarboxylic anhydride 1. Mechanism of a reaction between a diene and a dienophile.
Before we begin, there are a few things to consider when carrying out the reaction. In this experiment a dielsalder reaction was used to form the products. Organic chemistryintroduction to reactionsdielsalder. The title should be descriptive of the entire project, not. The dielsalder reaction is a concerted reaction, this means it occurs in only one step.
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