Interpretation: In the given intramolecular Diels-Alder reaction, the structural formula of the product has to be predicted.
Concept Introduction:
Diels-Alder reaction:
It is the reaction of conjugated dienes with double or triple bonded compounds which are known as “dienophiles”. The reaction is a
Example:
This mechanism shown that three
Diels-Alder reaction to form bicyclic system:
The Diels-Alder adduct formed in the Diels-Alder reaction can also be a bicyclic system which will be obtained when cylopentadiene is used as the diene as shown here:
In this reaction, the cylopentadiene acts as both diene and dienophile and formed a bicyclic system. When it is heated to
Intramolecular reaction:
In the word “Intramolecular”- “Intra”- means “within” or “in”. So an intramolecular reaction means the reaction is taking place within one molecule itself without the involvement of any other molecules.
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Chapter 20 Solutions
Organic Chemistry
- The aryl diene undergoes sequential Heck reactions to give a product with the molecular formula C15H18. Propose a structural formula for this product.arrow_forwardThe 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.arrow_forwardAldehydes and ketones react with thiols to yield thioacetals just as they react with alcohols to yield acetals. Predict the product of the following reaction, and propose a mechanism:arrow_forward
- Bicyclo-2,5-heptadiene can be prepared in two steps from cyclopentadiene and vinyl chloride. Provide a mechanism for each step.arrow_forwardWhen anthracene is added to the reaction of chlorobenzene with concentrated NaOH at 350 °C, an interesting Diels–Alderadduct of formula C20H14 results. The proton NMR spectrum of the product shows a singlet of area 2 around d 3 and abroad singlet of area 12 around d 7. Propose a structure for the product, and explain why one of the aromatic rings ofanthracene reacted as a dienearrow_forwarda-Tetralone undergoes Birch reduction to give an excellent yield of a single product. Predict the structure of the product, and propose a mechanism for its formation.arrow_forward
- Diphenylacetylene can be synthesized by the double dehydrohalogenation of 1,2-dibromo-1,2-diphenylethene. The sequence starting from (E)-1,2-diphenylethene consists of bromination to give the dibromide, followed by dehydrohalogenation to give a vinylic bromide, then a second dehydrohalogenation to give diphenylacetylene.(a) What is the structure, including stereochemistry, of the vinylic bromide?(b) If the sequence starts with (Z)-1,2-dibromo-1,2-diphenylethene, what is (are) the structure(s) of the intermediate dibromide(s)? What is the structure of the vinylic bromide?arrow_forwardPredict the products of the following reactions. (a) benzyl bromide + sodium cyanide (b) product of (a) + cyclopentylmagnesium bromide, then acidic hydrolysis (c) product of (a) + DIBAL-H, then hydrolysisarrow_forwardCyclohexene can be converted to 1-cyclopentenecarbaldehyde by the following series of reactions. Propose a structural formula for each intermediate compound.arrow_forward
- Enamines normally react with methyl iodide to give two products: one arising from alkylation at nitrogen and the second arising from alkylation at carbon. For example, Heating the mixture of C-alkylation and N-alkylation products gives only the product from C-alkylation. Propose a mechanism for this isomerization.arrow_forwardFollowing is a retrosynthetic analysis for an intermediate in the industrial synthesis of vitamin A. (a) Addition of one mole of HCl to isoprene gives 4-chloro-2-methyl-2-butene as the major product. Propose a mechanism for this addition and account for its regioselectivity. (b) Propose a synthesis of the vitamin A precursor from this allylic chloride and ethyl acetoacetate.arrow_forwardA compound gives the following IR spectrum. Upon reaction with sodium borohydride followed by acidification, it forms the product with the 1H NMR spectrum shown below. Identify the starting material and the productarrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning