Use retrosynthetic analysis to devise a synthesis of each of the following from the indica...

Use retrosynthetic analysis to devise a synthesis of each of the following from the indicated starting material and any necessary reagents.

(a)

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(b)

Sample Solution (a) The bond disconnection shown reveals the relationship between the carbon skeleton of the target and the given starting material.

Carbon–carbon bond formation between an ethyl anion equivalent and an electrophilic site on the side chain can be accomplished by the reaction between a primary alkyl bromide and lithium diethylcuprate.

The primary bromide can be prepared by free-radical addition of HBr to the prescribed starting material.