Diels-Alder reaction drawing product

Cyclopentadiene can react with itself in a Diels-Alder reaction. Draw the endo and exo products. 

Another class of reaction where you can see at once that the disconnection is the reverse of the reaction is Pericychc Reactions. An example would be the Diels-Alder reaction between butadiene and maleic anhydride. Draw the mechanism and the product. 

Assess the Diels-Alder reaction between cyclopentadiene and 1,3-butadiene, drawing structures for all likely products from the reaction. Suggest ways in which the selectivity of the reaction may be improved. 

In this they somewhat resemble the curly arrows used to show resonance. in benzene, where the arrows show where to draw the new bonds, and which ones not to draw in the canonical structure but in this case there is neither a sense of direction nor even an actual movement. The analogy between the resonance of benzene and the electron shift in the Diels-Alder reaction is not far fetched, but it is as well to be clear that one is a reaction, with starting materials and a product, and the other is not. 

In most cases, we don t even need to draw the charge-separated resonance forms to determine which orientation of the reactants is preferred. We can predict the major products of unsymmetrical Diels-Alder reactions simply by remembering that the electron-donating groups of the diene and the electron-withdrawing groups of the dienophile usually bear either a 1,2-relationship or a 1,4-relationship in the products, but not a 1,3-relationship. 

Draw a final diagram of the product with the stereochemistry of the other substituents shown too in the usual way. This is the endo product of the Diels-Alder reaction... 

The curly arrows are drawn clockwise, but they could equally well have been drawn anticlockwise. Thus, there is no absolute sense in which the hydrogen atom that moves from one carbon atom to the other in the ene reaction is a hydride shift, as seems to be implied by the clockwise curly arrow, or a proton shift, as it would seem to be if the arrows were to have been drawn in the opposite direction. In other words, neither component can be associated with the supply of electrons to any of the new bonds. The curly arrows therefore have a somewhat different meaning from those used in ionic reactions. They share with all curly arrows the function of showing where to draw the new bonds and which ones not to draw in the resulting structure. They are related to the arrows used to illustrate resonance in benzene, in having no sense of direction, but the Diels-Alder reaction has starting materials and a product, and aromatic resonance in benzene does not. 

Example Draw the product of the following Diels-Alder reaction ... 

Problem 16.18 Draw the product formed when each diene and dienophile react in a Diels-Alder reaction. 

Problem 16.22 Draw the products of each Diels-Alder reaction, and indicate the stereochemistry. 

Problem 16.25 Draw the product (A) of the following Diels-Alder reaction. A was a key intermediate in the synthesis of the addicting pain reliever morphine, isolated from the opium poppy. 

Draw the products of the following Diels-Alder reactions. Indicate stereochemistry where appropriate. 

Diels-Alder reaction of a monosubstituted diene (such as CH2=CH-CH=CHOCH3) with a monosubstituted dienophile (such as CH2=CHCH0) gives a mixture of products, but the 1,2-disubstituted product often predominates. Draw the resonance hybrid for each reactant and use the charge distribution of the hybrids to explain why the 1,2-disubstituted product is the major product. 

With this in mind, draw the product of each intramolecular Diels-Alder reaction. 

Draw the Product of a Diels-Alder Reaction 588 Benzene and Aromatic Compounds... 

Cyclopentadiene is obtained from the light oil from coal tar distillation but exists as the stable dimer, dicyclopentadiene, which is the Diels-Alder adduct from two molecules of the diene. Thus, generation of cyclopentadiene by pyrolysis of the dimer represents a reverse Diels-Alder reaction. See Figs. 1 and 2 for nmr and infrared spectra of dicyclopentadiene. In the Diels-Alder addition of cyclopentadiene and maleic anhydride the two molecules approach each other in the orientation shown in the drawing above, as this orientation provides maximal overlap of ir-bonds of the two reactants and favors formation of an initial ir-complex and then the final e do-product. Dicyclopentadiene also has the endo-configuration. 

Intramolecular Diels-Alder reactions can give endo or exo products. We should first discover which this is. Drawing the transition state for the endo product, we find that the endo product is indeed formed. So electronic factors dominate, perhaps because the dienophile has such a low-energy LUMO and has two carbonyl groups for secondary orbital overlap with the back of the diene. 

Stereospecificity, the property that the stereochemistry of the starting materials determines the stereochemistry of the product, is one of the hallmarks of pericyclic reactions. It is possible to draw two-step nonconcerted, polar or free-radical mechanisms for many pericyclic reactions, but these two-step mechanisms fail to account for the stereospecificity of the reactions. For example, a two-step polar mechanism can be drawn for the Diels-Alder reaction between 2-methoxybutadiene (a nucleophile) and ethyl cA-crotonatc (an electrophile). This mechanism proceeds through a dipolar intermediate in which one new cr bond has formed. In this intermediate, there is free rotation about the two C atoms of the dienophile, so the cis stereochemical relationship between the Me and CC Et groups is expected to be lost in the product. In fact, though, the product is exclusively cis. This finding does not completely rule out a polar mechanism— it is possible that the intermediate exists but that ring closure occurs more quickly than rotation about the cr bond—but it does limit the lifetime of the dipolar intermediate to such an extent that one can say practically that it does not exist. 

Pericyclic reactions can proceed under acidic or basic conditions. For example, the oxy-Cope rearrangement is greatly accelerated under basic conditions, and the Diels-Alder reaction is greatly accelerated by Lewis acids. Often a series of polar reactions is used to synthesize an unstable intermediate, which then undergoes a pericyclic reaction to reveal the product. In other words, a good command of polar mechanisms (Chapters 2 and 3) is essential to understanding how to draw pericyclic mechanisms. 

Q 4. An adduct I is formed by the Diels—Alder reaction of cyclopentadiene with ethyne. When I is treated with hexachlorocyclopentadiene (II), it forms the well-known pesticide, Aldrin (HI). Epoxidation of III with peracid produces another pesticide, Dieldrin (IV)- Draw strucmres of I, II, III, and IV and explain how these products are formed. 

Draw the product formed by the Diels-Alder reaction of 2,3-diphenyl-1,3-butadiene with methyl acrylate. 

The Diels-Alder reaction of 2S,4 -hexadiene and diethyl maleate generates four new stereogenic carbon centers. How many possible stereoisomers are there Draw all of them. Which one or ones can be expected to be the major product or products Briefly explain. 

N-Phenylmaleimide, the product prepared in Experiment [24B], can act as a dienophile in the Diels-Alder reaction (see Experiments [14] and [15]). Draw the structure of the product that would be formed by the treatment of N-phenylmaleimide with (a) 3-sulfolene under the conditions given in Experiment [14] and (b) furan. 

Draw a structural formula for the product of this Diels-Alder reaction, including the stereochemistry of the product. 

Problem 7.7. Draw and name the products expected in the Diels-Alder reaction between cyclopentadiene and 3-chloro-l-propene (allyl chloride [H2C=CH-CH2C1]). 

PROBLEM 20.37 Now, here s an interesting variation on the reaction of Problem 20.36. Diels-Alder additions typically take place as shown in Problem 20.36, with the ring-closed partner (A in the answer to Problem 20.36) actually doing the addition reaction. However, the molecule shown below is an exception, as the Diels-Alder reaction takes place in the normal way to give the product shown. Draw an arrow formalism for the reaction and then explain why 1 reacts differently from other cycloheptatrienes. 

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