16. Conjugated Systems

Predict the product of the Claisen reactions shown.

(b)

Propose a mechanism for the following reaction:

In the Claisen rearrangement of allyl phenyl ether, what is the major organic product formed?

Draw the product of the following reaction:

The Claisen rearrangement can be used to attach allyl groups to benzene via initial alkylation of a phenol.

(a) Predict the identity of A and B

(b) provide an arrow-pushing mechanism for each step. [The phenol alkylation is simply a Williamson ether synthesis reaction.]

The Eschenmoser–Claisen reaction is a variant of the Claisen reaction studied in this chapter. Based on your answers to Assessments 22.53–22.55, predict a product of this reaction.

If the terminal sp² carbon of the substituent attached to the benzene ring is labeled with ¹⁴C, where will the label be in the product?

Predict the product of the Claisen reactions shown.

(c)

Only after working Assessment 22.53, predict the product of the following reactions.

(b)

Only after working Assessment 22.53, predict the product of the following reactions.

(a)

The Ireland–Claisen reaction is a variant of the Claisen reaction studied in this chapter.

(a) Suggest a mechanism for the first step.

(b) Predict the product (B) that would result from heating intermediate A.

(c) Hydrolysis of B gives a carboxylic acid.

Suggest a mechanism for this reaction.

The Johnson–Claisen reaction is a variant of the Claisen reaction studied in this chapter. (a) Suggest a mechanism for the first step. (b) Predict the product (B) that would result from heating intermediate A.