Concept explainers
(a)
Interpretation: The compounds are formed by the tandem reaction with given substrates are to be predicted.
Concept introduction: The ring-closing metathesis (RCM) by Grubbs catalyst occurs, when the starting material is diene. This reaction is facilitated under high-dilution condition as it favors intramolecular metathesis instead of intermolecular metathesis.
(b)
Interpretation: The synthesis of the substrate in part (b) that uses a Diels–Alder reaction with diethylmaleate as the dienophile is to be devised.
Concept introduction: Diels-alder reaction is a cycloaddition reaction in which two molecules combine to form a new ring. In this type of reaction, syn addition takes place. It is a reaction between diene with a dienophile to yield a cyclohexene. The dienophile adds to one side of the diene, and diene adds to the one side of the dienophile. Thus, they have syn stereochemistry.
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- 2) The Diels-Alder reaction, developed by German chemists Otto Diels and Kurt Alder (who received the Nobel Prize in 1950 for their discovery), has great synthetic importance due to the possibility of forming an unsaturated six-membered cycle without involving intermediates ionic. About the reaction, answer: (a) Indicate the reagents necessary for the synthesis of the following compounds, indicating who is the diene and who is the dienophile.arrow_forwardDraw and discuss the mechanism (with arrows to show electron movements) of the Diels-Alder reaction between anthracene and maleic anhydride. Draw the orientation and phases of the reacting p-orbitals showing how they overlap in a “suprafacial” geometry to form productarrow_forward4.35 Formulate the reaction of cyclohexene with (i) Br2 and (ii) meta-chloro- peroxybenzoic acid followed by H30+. Show the reaction intermediates and the final products with correct cis or trans stereochemistry. 4.36 What products would you expect to obtain from reaction of cyclohexa- 1,3-diene with each of the following? (a) 1 mol Br2 in CH2C12 (c) 1 mol DCl (D = deuterium, ²H) (b) 1 mol HCl (d) 2 mol H2 over a Pd catalyst 4.37 Predict the products of the following reactions on hex-1-yne: (a) 1 equiv HBr ? (b) 1 equiv Cl2 ? (c) H2, Lindlar catalystarrow_forward
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- When heated, allyl aryl ethers and allyl vinyl ethers undergo a reaction called a Claisen rearrangement, a concerted reorganization of bonding electrons similar to the Diels-Alder reaction. The reaction proceeds through a six-membered, cyclic transition state. Draw the structure of the expected product when this compound undergoes a Claisen rearrangement. You do not have to consider stereochemistry. For the purposes of this problem, assume that double bonds in an aromatic ring are localized at the positions indicated in the figure. Include isomerization to a phenol IF appropriate.arrow_forwardWhen heated, allyl aryl ethers and allyl vinyl ethers undergo a reaction called a Claisen rearrangement, a concerted reorganization of bonding electrons similar to the Diels-Alder reaction. The reaction proceeds through a six-membered, cyclic transition state. Draw the structure of the expected product when this compound undergoes a Claisen rearrangement. You do not have to consider stereochemistry. For the purposes of this problem, assume that double bonds in an aromatic ring are localized at the positions indicated in the figure. Include isomerization to a phenol IF appropriate.arrow_forward4arrow_forward
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- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning