20.33 Think-Pair-Share(a) Rank the following dienes and dienophiles in order of increasing reactivity in theDiels-Alder reaction.(i)CO₂Et(ii)COEt||CO₂EtMeOMeO(b) Draw the product that results from the most reactive diene and most reactivedienophile shown in part (a).(c) Draw a depiction of the orbital overlap involved in the pericyclic reaction that oc-curs between the diene and dienophile in part (b).(d) Is the major product formed in part (b) the endo or exo configuration? Explainyour reasoning.

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Answered: 20.33 Think-Pair-Share (a) Rank the…

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter30: Orbitals And Organic Chemistry: Pericyclic Reactions

Section30.SE: Something Extra

Problem 17MP

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The Diels-Alder reaction is not the only pericyclic reaction involving the cyclic flow of six electrons over six atoms. Other examples include electrocyclic reactions, Cope rearrangements, and Claisen rearrangements, the (a) ? Нeat Electrocyclic reaction curved arrow notations for which are shown here. Complete each of these reactions by drawing the product. (b) Cope rearrangement Нeat (c) Claisen rearrangement Нeat
In the following nucleophilic substitution reaction, does the top or bottom have the higher reaction rate. Why?
Resveratrol is an antioxidant found in the skin of red grapes. Its anticancer, anti-inammatory, and various cardiovascular effects are under active investigation. (a) Draw all resonance structures for the radical that results from homolysis of the OH bond shown in red. (b) Explain why homolysis of this OH bond is preferred to homolysis of either OH bond in the other benzene ring.
(a) What monobromo allylic substitution products would result from reaction of each of PRACTICE P the following compounds with NBS in the presence of peroxides and/or light? (b) In the case of isomeric products for any reaction, which would you predict to be the most stable based on the double bond in the product? (c) Draw the resonance hybrid(s) for the allylic radical that would be involved in each reaction. (i) (ii) V dil.... (iii) oily
11.; (a) Similar to alkanes, hydrogen gas can undergo radical bromination according to the reaction below. Propose a chain-reaction mechanism for this reaction, including an initiation step, propagation steps, and two plausible termination steps. The homolytic bond dissociation energy for Br-Br is 46 kcal·mole', for H-Br is 88 kcal'mole and for H-H is 104 kcal'mole'. hv H-H + Br-Br 2 H-Br (b) Calculate the overall AH for the above propagation steps (show all work).
Alkenes can be converted to alcohols by hydroboration-oxidation. (a) Draw the structure of the alcohol or alcohols formed in the reaction sequence. Clearly indicate stereochemistry by drawing a wedged bond, a dashed bond and two O Hint in-plane bonds per each chiral carbon. Draw hydrogen atoms that are connected to wedge-and-dash bonds.(b) Characterize the product or products of the reactions. The first step of the reaction, hydroboration, involves addition of BH, to the double bond, with -BH, attached to one carbon and hydrogen Be sure to draw hydrogens on oxygen, where applicable. attached to the other. Consider both Rings the regioselectivity and the Select Draw More Erase stereochemistry of this addition. H Diborane, B,H,, is a source of borane, BH,, and can be used 1. B2H6, interchangeably. Diglyme is a solvent. diglyme 2. H2О2, НО", The product or products of the reaction are characterized as being O S. O racemic. O achiral. O R,S (and/or S,R). O R. O S,S. O R.R. O diastereomers.
There are two isomeric cyclohexa-1,4-diene products when benzoic acid undergoes the Birch reduction (see Problem 25.24). (a) Draw the mechanism that leads tothe formation of the major product. (b) Will the Birchreduction of benzoic acid occur faster or slower than theBirch reduction of benzene itself? Hint: Is –CO2H anelectron-donating or an electron-withdrawing group?
The bicyclic heterocycles quinoline and indole undergo electrophilic aromatic substitution to give the products shown. (a) Explain why electrophilic substitution occurs on the ring without the N atom for quinoline, but occurs on the ring with the N atom in indole. (b) Explain why electrophilic substitution occurs more readily at C8 than C7 in quinoline. (c) Explain why electrophilic substitution occurs more readily at C3 rather than C2 of indole.
Complete the following reaction scheme. Give all product(s) and indicate major or minor and any relevant stereochemistry (d) dil HCl (e) ОН Conc H2SO4 heat (f) HBr
1. The conversion between alcohols, ethers, and epoxides is an important process in organic synthesis. (a) Draw a mechanism for the classic epoxidation of an alkene using MCPBA. (b) Show how this epoxidation can be converted to alcohols/ethers using both acidic and basic conditions. Be sure to highlight the difference between regio- and stereochemistry with the different reactions. (c) Name the end products and be sure to include all necessary stereochemistry. MCPBA CH3OH +H O + Diastereomer SN 1 CH₂ONa SN 2 ↓ OH OCH3 um OCH 3
addition of hbr to a double bond with an ether (-or) substituent occurs regiospecifically to give a product in which the Br OR are bonded to the same carbon. Draw the two possible carbocation intermediates in this electrophilic addition reaction,and explain using resonance why the observed product is formed.
There are two isomeric cyclohexa-1,4-diene products when toluene undergoes the Birch reduction (see Problem 25.24). (a) Draw the mechanism that leads to the formation of the major product. (b) Will the Birchreduction of toluene occur faster or slower than the Birch reduction of benzene itself? Hint: Is –CH3 an electron-donating or an electron-withdrawing group?

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