25. Condensation Chemistry

What reagents should be used to prepare the following compounds?

a.

Which of the following pairs of starting materials can be used to synthesize ${\mathrm{CH}}_3\mathrm{COCH}{2}_2\mathrm{CH}{2}_1\mathrm{COOEt}$ via a Michael addition reaction?

Determine the product in the following conjugated addition reaction.

Determine the product in the following conjugated addition reaction.

Determine the product in the following conjugated addition reaction

What reagents should be used to prepare the following compounds?

b.

A compound known as Hagemann's ester can be prepared by treating a mixture of formaldehyde and ethyl acetoacetate first with base and then with acid and heat. Write the structure for the product of each of the steps.

b. The second step is a Michael addition.

Draw the products of the following reactions:

a.

The following reaction was used in the synthesis of aculeatin A, a natural product that is active against KB cell lines. Although it only worked under acidic conditions, a mechanism can be drawn where the reaction might proceed under basic conditions. Suggest this mechanism (J. Org. Chem. 2014, 79, 1498–1504). [The most acidic proton is indicated . . . and number your carbons!]

Show how the following products might be synthesized from suitable Michael donors and acceptors.

(c)

Show how the following products might be synthesized from suitable Michael donors and acceptors.

(b)

Show how the following products might be synthesized from suitable Michael donors and acceptors.

(a)

Predict the products from this sequence of reactions.

Lawsone, found in the extract of henna, reacts with amino acid residues to give the characteristic color associated with henna tattoos. Suggest a mechanism for the reaction shown.