Q70E - Organic Chemistry (Mcmurry)

Question

How would you prepare the following compounds from cyclohexanone?

Step-by-Step Solution

Answer

1. Cyclohexanone has α hydrogen atom. Therefore it can undergo aldol condensation reaction. Two times of aldol condensation with two molecules of benzaldehyde, cyclohexanone gives the desired product.
2. Treating the cyclohexanone with pyrrolidine gives an enamine. Then the enamine undergoes Michael addition with vinylnitryl and gives the desired product. 
3. The ethoxide ion removes α-hydrogen from the cyclohexanone and forms a carbanion. Then the carbanion performs a neucleophilic attack on 3-bromo-1-butene and removes the bromide ion and gives the desired product.
4. The ethoxide ion abstracts α-carbon from the cyclohexanone and forms an enolate. Then the enolate performs a neucleophilic attack on diethyl oxalate followed by hydrolysis gives the desired product.

 

Answer of subpart (a): Preparation of the compound from cyclohexanone

Explanation of the preparation

Cyclohexanone has α hydrogen atom. Therefore it can undergo aldol condensation reaction. Two times of aldol condensation with two molecules of benzaldehyde, cyclohexanone gives the desired product.

Answer of subpart (b): Preparation of the compound from cyclohexanone

Explanation of the preparation

Treating the cyclohexanone with pyrrolidine gives an enamine. Then the enamine undergoes Michael addition with vinylnitryl and gives the desired product. 

Answer of subpart (c): Preparation of the compound from cyclohexanone

Explanation of the preparation

The ethoxide ion removes α-hydrogen from the cyclohexanone and forms a carbanion. Then the carbanion performs a neucleophilic attack on 3-bromo-1-butene and removes the bromide ion and gives the desired product.

Answer of subpart (d): Preparation of the compound from cyclohexanone

Explanation of the preparation

The ethoxide ion abstracts α-carbon from the cyclohexanone and forms an enolate. Then the enolate performs a neucleophilic attack on diethyl oxalate followed by hydrolysis gives the desired product.