Interpretation:
The observation that stereochemistry of the product formed when dimethylbutynedioate undergoes Diels-Alder reaction with (2E,4Z) 2.4-hexadiene is different from that obtained from (2E,4E) isomer is to be explained.
Concept introduction:
In Diels-Alder reaction, a dienophile reacts with a diene to yield a cyclic adduct. The reaction takes place through 1,4 addition of the dienophile into the diene through a cyclic transition state. These reactions occur rapidly with dienophiles having electron withdrawing substituent groups in conjugation with the double bond and if the diene adapts a s-cis conformation during the reaction.
To explain:
The observation that stereochemistry of the product formed when dimethylbutynedioate undergoes Diels-Alder reaction with (2E,4Z) 2.4-hexadiene is different from that obtained from (2E,4E) isomer.
Want to see the full answer?
Check out a sample textbook solutionChapter 14 Solutions
Organic Chemistry
- When Br2 is added to buta-1,3-diene at -15 °C, the product mixture contains 60% ofproduct A and 40% of product B. When the same reaction takes place at 60 °C, theproduct ratio is 10% A and 90% B.(a) Propose structures for products A and B. (Hint: In many cases, an allylic carbocationis more stable than a bromonium ion.)arrow_forwardPredict the major products of the following reactions, including stereochemistry where appropriate. ) cyclopentylmethanol + CrO3 # pyridine # HClarrow_forwardDraw the product of each electrocyclic reaction.a. the thermal electrocyclic ring closure of (2E,4Z,6Z)-nona-2,4,6-trieneb. the photochemical electrocyclic ring closure of (2E,4Z,6Z)-nona-2,4,6-trienec. the thermal electrocyclic ring opening of cis-5-ethyl-6-methylcyclohexa-1,3-diened. the photochemical electrocyclic ring opening of trans-5-ethyl-6-methylcyclohexa-1,3- dienearrow_forward
- When 1 mole of buta-1,3-diene reacts with 1 mole of HBr, both 3-bromobut-1-ene and 1-bromobut-2-ene are formed. Propose a mechanism to account for this mixture of products.arrow_forwardPredict the major products of the following reactions. Include appropriate stereochemistry in the product structures. S-1,3-dimethylcyclohexene + aqueous Hg(OAc)2Hg(OAc)2 followed by treatment with NaBH4arrow_forwardShow the stereochemistry of the epoxide (see Problem 11-31) you would obtain by formation of a bromohydrin from trans-2-butene, followed by treatment with base.arrow_forward
- A 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. Draw the products obtained from each free-radical intermediate.arrow_forwardList the following compounds in order of reactivity towards MeOH (1 = highest, 4 =lowest) and propose a quantitative explanation why.arrow_forwardWhen Br2 is added to buta-1,3-diene at -15 °C, the product mixture contains 60% ofproduct A and 40% of product B. When the same reaction takes place at 60 °C, theproduct ratio is 10% A and 90% B.(a) Propose structures for products A and B. (Hint: In many cases, an allylic carbocationis more stable than a bromonium ion.)(b) Propose a mechanism to account for formation of both A and B.(c) Show why A predominates at -15 °C and B predominates at 60 °C.(d) If you had a solution of pure A, and its temperature were raised to 60 °C, what wouldyou expect to happen? Propose a mechanism to support your predictionarrow_forward
- Predict the products of conjugate (Michael) additions, and show how to use thesereactions in syntheses. Show the general mechanism of the Robinson annulation,and use it to form cyclohexenone ring systems.arrow_forwardPredict the major products of the following reactions, including stereochemistry where appropriate. sodium ethoxide + 1@bromobutanearrow_forwardWhen Br2 is added to buta-1,3-diene at -15 °C, the product mixture contains 60% ofproduct A and 40% of product B. When the same reaction takes place at 60 °C, theproduct ratio is 10% A and 90% B.If you had a solution of pure A, and its temperature were raised to 60 °C, what wouldyou expect to happen? Propose a mechanism to support your prediction.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning