Concept explainers
(a)
Interpretation:
The transformation with equation formed by the Diels-Alder reaction between
Concept introduction:
Diels-Alder reaction is a reaction between conjugated diene and
(b)
Interpretation:
Whether the Diels-Alder reaction of
Concept introduction:
Diels-Alder reaction is a reaction between conjugated diene and alkene. It is also known as
In the given conditions of the reaction, if the products of any reaction do not attain the equilibrium then the reaction is known as kinetically controlled reaction.
In the given conditions of the reaction, if the products of any reaction attain the equilibrium then the reaction is known as thermodynamically controlled reaction.
(c)
Interpretation:
The two diagrams which show the transition state that results in the formation of the endo product, and the other showing the transition state that leads to the exo product are to be drawn. The diagram that shows the transition state of the reaction at low temperature is to be stated.
Concept introduction:
Diels-Alder reaction is a reaction between conjugated diene and alkene. It is also known as
In the given conditions of the reaction, if the products of any reaction do not attain the equilibrium then the reaction is known as kinetically controlled reaction.
In the given conditions of the reaction, if the products of any reaction attain the equilibrium then the reaction is known as thermodynamically controlled reaction.
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Organic Chemistry
- Step 6: Now that you have determined the substrates and mechanism of a Diels-Alder reaction, you will learn how to recognize when you should use the Diels-Alder reaction. In a synthesis reaction, if you are given a cyclohexene product with no other obvious functional group transformations and an electron-withdrawing group two carbons away from the alkene, it is likely made via the Diels-Alder reaction. Deduce the structures of the starting materials to form the Diels-Alder adduct shown. ..... CN CN Diene + Dienophilearrow_forwardWhen heated, allyl aryl ethers and allyl vinyl ethers undergo a reaction called a Claisen rearrangement, a concerted reorganization of bonding electrons similar to the Diels-Alder reaction. The reaction proceeds through a six-membered, cyclic transition state. Draw the structure of the expected product when this compound undergoes a Claisen rearrangement. You do not have to consider stereochemistry. For the purposes of this problem, assume that double bonds in an aromatic ring are localized at the positions indicated in the figure. Include isomerization to a phenol IF appropriate.arrow_forwardWhen heated, allyl aryl ethers and allyl vinyl ethers undergo a reaction called a Claisen rearrangement, a concerted reorganization of bonding electrons similar to the Diels-Alder reaction. The reaction proceeds through a six-membered, cyclic transition state. Draw the structure of the expected product when this compound undergoes a Claisen rearrangement. You do not have to consider stereochemistry. For the purposes of this problem, assume that double bonds in an aromatic ring are localized at the positions indicated in the figure. Include isomerization to a phenol IF appropriate.arrow_forward
- Following is an example of a type of reaction known as a Diels-Alder reaction 1,3-Pentadiene Ethylene 3-Methylcyclohexene (a racemic mixture) The Diels-Alder reaction between a diene and an alkene is quite remarkable in that it is one of the few ways that chemists have to form two new carbon-carbon bonds in a single reaction. Given what you know about the relative strengths of carbon-carbon sigma and pi bonds, would you predict the Diels-Alder reaction to be exothermic or endothermic? Explain your reasoning.arrow_forwardMechanism The Diels-Alder reaction is part of a class of reactions known as a cycloaddition reaction. This reaction is specifically a [4+2] cycloaddition which is a concerted (one-step) process in which two new carbon - carbon sigma bonds are formed from two pi bonds. For the first Diels - Alder step of the mechanism fill in the arrows needed for the transformation. The rest of the mechanism is drawn for you. OH Show mechanism arrows for this step! 4 + 2 cycloaddition OH H D- & H+ transfer OH Nuc acyl substitution H L.G.arrow_forwardDraw the reactants that would be used to form this cyclohexene derivative in a Diels- Alder reaction. Include any relevant stereochemical configurations. Draw Diene + ·00 aarrow_forward
- Zingiberene and β-sesquiphellandrene, natural products obtained from ginger root, contain conjugated diene units. Which diene reacts faster in the Diels–Alder reaction and why?arrow_forwardThe following is an example of a hetero Diels-Alder reaction, because a noncarbon atom (in this case, an N atom) is involved in bond formation and bond breaking. Draw the curved arrows necessary to account for this transformation. OCH3 OCH3 + N- Hydroquinone, benzene, 25 °C, 90 min 86%arrow_forwardA student adds NBS to a solution of 1-methylcyclohexene and irradiates the mixture with a sunlamp until all the NBS has reacted. After a careful distillation, the product mixture contains two major products of formula C7H11Br. (a) Draw the resonance forms of the three possible allylic free radical intermediates.arrow_forward
- 1,3-Butadiene is a gas at room temperature that requires a gas-handling apparatus to use in a Diels-Alder reaction. Butadiene sulfone is a convenient substitute for gaseous 1,3-butadiene. This sulfone is a solid at room temperature (mp 66°C), and when heated above its boiling point of 110°C, it decomposes by a reverse Diels-Alder reaction to give cis-1,3-butadiene and sulfur dioxide. Draw Lewis structures for butadiene sulfone and SO, then show by curved arrows the path of this reaction, which resembles a reverse Diels-Alder reaction. 140°C SO2 Butadiene sulfone 1,3-Butadiene Sulfur dioxidearrow_forwardFuran and maleimide undergo a Diels–Alder reaction at 25 °C to give the endo isomer of the product. When the reactiontakes place at 90 °C, however, the major product is the exo isomer. Further study shows that the endo isomer of theproduct isomerizes to the exo isomer at 90 °C.furan: O maleimide:OON H(a) Draw and label the endo and exo isomers of the Diels–Alder adduct of furan and maleimide.(b) Which isomer of the product would you usually expect from this reaction? Explain why this isomer is usually favored.(c) Examine your answer to (b) and determine whether this answer applies to a reaction that is kinetically controlled orone that is thermodynamically controlled, or both.(d) Explain why the endo isomer predominates when the reaction takes place at 25 °C and why the exo isomer predominates at 90 °Carrow_forwardAccount for the regioselectivity and stereoselectivity observed when this compound is treated with Br2 in H₂O by drawing the final product in the reaction. • Use wedge and hash bonds ONLY when needed to show reaction stereochemistry. • If the reaction produces a racemic mixture, just draw one stereoisomer.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning