Interpretation:
The observation that photolysis of cis-cyclobutene yields cis-cyclododecaen-7-yne but photolysis of trans-cyclobutene yields trans-cyclododecaen-7-yne is to be explained by identifying the type and stereochemistry of the pericyclic reaction involved.
Concept introduction:
An electrocyclic reaction involves the cyclization of a conjugated acyclic system. These reactions are reversible and are highly stereospecific.
In elecrocyclic reactions involving even number of electron pairs, a thermal reaction occurs in conrotatory manner and a photochemical reaction occurs in disrotatory manner.
In elecrocyclic reactions involving odd number of electron pairs, a thermal reaction occurs in disrotatory manner and a photochemical reaction occurs in conrotatory manner.
Want to see the full answer?
Check out a sample textbook solutionChapter 30 Solutions
Organic Chemistry
- Bicyclo-2,5-heptadiene can be prepared in two steps from cyclopentadiene and vinyl chloride. Provide a mechanism for each step.arrow_forwardIdentify the following pericyclic reaction; explain the course, product distribution and stereochemistry of the reaction. Where the first product is produced 70% and the second product is produced 30%.arrow_forwardWhen cyclohexene is treated with m-chloroperbenzoic acid and H,0, trans-cyclohexane-1,2-diol is produced. Propose a mechanism for this reaction, accounting for the observed stereochemistry. Hint: Recall what a МСРВА + Enantiomer H2O "OH peroxyacid does to an alkene.arrow_forward
- Para-substituted product was produced when phenol reacts with cyclohexanecarbonyl bromide in the presence of AIB13. -Br Cyclohexanecarbonyl bromide (i) Outline the mechanism for this reaction. (ii) Draw the alternative substituted product formed.arrow_forwardOn treatment with HBr, vinylcyclohexane undergoes addition and rearrangement to yield 1-bromo-l-ethylcyclohexane. Using curved arrows, propose a mechanism to account for this result.arrow_forwardShow how the following starting material is converted to the given product by a series of two pericyclic reactions. Account for the observed stereochemistry.arrow_forward
- Identify the following pericyclic reaction; explain the course and stereochemistry of the reaction.arrow_forwardTreating cyclohexene with HBr in the presence of acetic acid gives bromocyclohexane (85%) and cyclohexyl acetate (15%). Br OCCH CH,COH + HBr Bromocyclohexane Cyclohexyl acetate (15%) Cyclohexene (85%) Propose a mechanism for the formation of the latter product.arrow_forwardWhich of the following reaction sequences would you use to convert 1- methylcyclohexene to the product 2 ? OH 2 O A) Oxymercuration-Demercuration O B) Hydroboration-Oxidation O C) Os04 / Pyridinc- NalHSO3 O D CH3CO3H- H30+arrow_forward
- One compound that contributes to the “seashore smell” at beaches in Hawai‘i is dictyopterene D', a component of a brown edible seaweed called limu lipoa. Hydrogenation of dictyopterene D' with excess H2 in the presence of a Pd catalyst forms butylcycloheptane. Ozonolysis with O3 followed by (CH3)2S forms CH2(CHO)2, HCOCH2CH(CHO)2, and CH3CH2CHO. What are possible structures of dictyopterene D'?arrow_forwardSuggest a mechanism for the following reactions. Each will require multiple types of concerted pericyclic reactions (cycloaddition, electrocyclic, and sigmatropic. Classify each reaction type. Me3Si Me3Si Me Si Me Sil g Harrow_forwardOn treatment with HBr, 3-Methyl-1-pentene undergoes addition and rearrangement to yield 3-Bromo-3-methylpentenearrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning