Give the expected products for the aldol condensations of (b) phenylacetaldehyde.

Give the expected products for the aldol condensations of (c) pentan-3-one.

Propose a complete mechanism for the acid-catalyzed aldol condensation of acetone.

Propose a mechanism for the dehydration of diacetone alcohol to mesityl oxide

(a) in acid.

(b) in base.

Predict the products of aldol condensation, followed by dehydration, of the following ketones and aldehydes.

(a) butyraldehyde

Predict the products of aldol condensation, followed by dehydration, of the following ketones and aldehydes.

(b) acetophenone

Predict the products of aldol condensation, followed by dehydration, of the following ketones and aldehydes.

(c) cyclohexanone

Propose mechanisms for the following base-catalyzed condensations, with dehydration.

(a) 2,2-dimethylpropanal with acetaldehyde

Propose mechanisms for the following base-catalyzed condensations, with dehydration.

(b) benzaldehyde with propionaldehyde

Predict the major products of the following base-catalyzed aldol condensations with dehydration.

(a) benzophenone (PhCOPh) + propionaldehyde

Predict the major products of the following base-catalyzed aldol condensations with dehydration.

(b) 2,2-dimethylpropanal + acetophenone

Show how octane-2,7-dione might cyclize to a cycloheptenone. Explain why ring closure to the cycloheptenone is not favored.

When cyclodecane-1,6-dione is treated with sodium carbonate, the product gives a UV spectrum similar to that of 1-acetyl-2-methylcyclopentene. Propose a structure for the product, and give a mechanism for its formation.

Show how each compound can be dissected into reagents joined by an aldol condensation, then decide whether the necessary aldol condensation is feasible.

(a)

Show how each compound can be dissected into reagents joined by an aldol condensation, then decide whether the necessary aldol condensation is feasible.

(b)

Show how each compound can be dissected into reagents joined by an aldol condensation, then decide whether the necessary aldol condensation is feasible.

(c)

Show how each compound can be dissected into reagents joined by an aldol condensation, then decide whether the necessary aldol condensation is feasible.

(e)

The following compound results from base-catalyzed aldol cyclization of a 2-substituted cyclohexanone.

(a) Show the diketone that would cyclize to give this product.

The following compound results from base-catalyzed aldol cyclization of a 2-substituted cyclohexanone.

(b) Propose a mechanism for the cyclization.

Ethoxide is used as the base in the condensation of ethyl acetate to avoid some unwanted side reactions. Show what side reactions would occur if the following bases were used.

(a) sodium methoxide

(b) sodium hydroxide

Esters with only one α hydrogen generally give poor yields in the Claisen condensation. Propose a mechanism for the Claisen condensation of ethyl isobutyrate, and explain why a poor yield is obtained.

Predict the products of self-condensation of the following esters.

(a) methyl propanoate + NaOCH₃

(b) ethyl phenylacetate + NaOCH2CH₃

Predict the products of self-condensation of the following esters.

(c)

Predict the products of self-condensation of the following esters.

(d)

Propose a mechanism for the self-condensation of methyl 3-phenylpropionate promoted by sodium methoxide.

Show what esters would undergo Claisen condensation to give the following β-keto esters.

(a)

Show what esters would undergo Claisen condensation to give the following β-keto esters.

(b)

Show what esters would undergo Claisen condensation to give the following β-keto esters.

(c)

Propose mechanisms for the two Dieckmann condensations just shown.

Propose mechanisms for the two Dieckmann condensations just shown.