Sulfolene is a precursor for 1,3-butadiene in this experiment. It reacts by a “cycloreversion" reaction (think reverse Diels-Alder). Draw the mechanism that shows the formation of 1,3- butadiene from sulfolene. 140°C SO2 + Once 1,3-butadiene forms, it can participate in the Diels-Alder reaction. Draw the mechanism for the Diels-Alder reaction. 140°C If you measured the optical rotation of the Diels-Alder product, you would observe no optical activity. Why not?

Sulfolene is a precursor for 1,3-butadiene in this experiment. It reacts by a “cycloreversion" reaction (think reverse Diels-Alder). Draw the mechanism that shows the formation of 1,3- butadiene from sulfolene. 140°C SO2 + Once 1,3-butadiene forms, it can participate in the Diels-Alder reaction. Draw the mechanism for the Diels-Alder reaction. 140°C If you measured the optical rotation of the Diels-Alder product, you would observe no optical activity. Why not?

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter20: Dienes, Conjugated Systems, And Pericyclic Reactions

Section: Chapter Questions

Problem 20.35P: The following triene undergoes an intramolecular Diels-Alder reaction to give a bicyclic product....

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Mechanism 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.
The 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%
True or False: Acetylene is a naturally occurring conjugated diene True or False: The Diels-Alder reaction has the stereochemistry of the dienophile is retained in the product. True or False: When looking at kinetic vs. thermodynamic products the kinetic product predominates at low temperature. True or False: the mechanism of the Diels-Alder reaction is three π bonds break; one σ bond and two π bonds form.
Compounds P and Q can undergo a Diels-Alder reaction to form two regioisomeric products R and S as shown in Figure 5. OMe O C8H12O2 R C8H12O2 S Figure 5 Draw the chemical structures of regioisomeric compounds R and S. Using possible resonance contributors of P and Q predict which of the two regioisomers will be favoured in the reaction. Using curly arrows, draw the mechanism for the reaction of P and Q to form the dominant regioisomer you have predicted in your answer to part (ii) above.
7. At room temperature cyclopentadiene reacts with itself to form dicyclopentadiene in a Diels-Alder reaction. a) draw the self reaction of cyclopentadiene 20°C. b) When dicyclopentadiene is heated to boiling (170°C), the retor-Diels-Alder reaction occurs producing 2 moles of cyclopentadiene. Explain this observation in terms of free energy, enthalpy and entropy. c) If the AHxn = -75 kJ/mol and the ASpxn = -226 J/mol K, What temperature would be required for the reaction to be at equilibrium (Keq = 1).
8) Predict the two products that form in following Diels-Alder reaction Circle the major product. CH₂O CH₂OCH, H O₂N
The following triene undergoes an intramolecular Diels-Alder reaction to give a bicyclic product. Propose a structural formula for the product. Account for the observation that the Diels-Alder reaction given in this problem takes place under milder conditions (at lower temperature) than the analogous Diels-Alder reaction shown in Problem 20.34.
A) Write the mechanism and predict the products for the following reaction. Label each product as the thermodynamic product or the kinetic product. Write a few sentences explaining which product would predominate at low temperature and which would predominate at high temperature and explain the reason for this result. HBr ABd B) Choose reagents that would give the following product in a Diels-Alder reaction: C) Predict the major and minor product for the following Diels-Alder reaction:
Draw the structure of the product of the Diels-Alder reaction below. H3C CH3 O || O || + CH3OC-CEC-COCH3
6) The Diels-Alder reaction of anthracene (which is achiral) and maleic anhydride (also achiral) results in the formation of an achiral product. This is not always the case (where two achiral reactants form an achiral product). a) Propose a Diels-Alder reaction where two achiral starting materials result in the formation of a chiral product. b) Would this chiral product be a single enantiomer or a racemic mixture?
Diels—Alder reaction of a monosubstituted diene (such as CH2 = CH – CH = CHOCH3) with a monosubstituted dienophile (such as CH2 = CHCHO) 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.
Draw the structure of the product of the Diels-Alder reaction below. OCH3 H₂C 11 NO-C=C-CN