25. Condensation Chemistry

Propose mechanisms for the following reactions.

(d)

The base-catalyzed reaction of an aldehyde (having no α hydrogens) with an anhydride is called the Perkin condensation. Propose a mechanism for the following example of the Perkin condensation. (Sodium acetate serves as the base.)

The base-catalyzed reaction of an aldehyde (having no α hydrogens) with an anhydride is called the Perkin condensation. Propose a mechanism for the following example of the Perkin condensation. (Sodium acetate serves as the base.)

Show how you would use Robinson annulations to synthesize the following compounds. Work backward, remembering that the cyclohexenone is the new ring and that the double bond of the cyclohexenone is formed by the aldol with dehydration. Take apart the double bond, then see what structures the Michael donor and acceptor must have.

(a)

Show how you would use Robinson annulations to synthesize the following compounds. Work backward, remembering that the cyclohexenone is the new ring and that the double bond of the cyclohexenone is formed by the aldol with dehydration. Take apart the double bond, then see what structures the Michael donor and acceptor must have.

(b)