Q62E - Organic Chemistry (Mcmurry)

Question

How would you prepare the following substances from 2-cyclohexenone? More than one step may be needed.

a. 

b. 

c. 

d.  

Step-by-Step Solution

Answer

a. 

b.  

c. 

d. 

Reactions of Ketones

One of the name reactions for ketone is the Wolf-Kishner reaction, where the reagent used is ${\mathbf{H}}_{\mathbf{2}}{\mathbf{NNH}}_{\mathbf{2}}$/KOH, and the conversion of the ketone to alkane is observed. The reagent used for unsaturated ketones is the Gilman reagent, where the conjugate addition to $\alpha$, $\beta$ unsaturated ketones happens.

The compound (a) formed from cyclohexanone

a. The Wolff-Kishner reaction occurs when cyclohexanone undergoes a reaction with ${\text{H}}_{\text{2}}{\text{NNH}}_{\text{2}}$/KOH, and the product formed is cyclohexene. The ketone group is converted into an alkane.

                                          Wolff-Kishner reaction

The compound (b) formed from cyclohexanone

b. The given compound is formed when cyclohexanone is treated with Gilman reagent. Here, the conjugate addition to $\alpha$, $\beta$ unsaturated ketones by the Gilman reagent takes place. The reaction performed is shown below,

                       Addition of Gilman reagent to cyclohexanone

The compound (c) formed from cyclohexanone

c. The given compound is formed in two steps. In the first step, cyclohexanone is treated with Gilman reagent, and conjugate addition to $\alpha$, $\beta$ unsaturated ketone occurs. Now, the compound formed undergoes oxidation with ${\text{KMnO}}_{\text{4}}$, and the alkene group is converted into a carboxylic acid.

Addition of Gilman reagent and oxidation with ${\text{KMnO}}_{\text{4}}$

The compound (d) formed from cyclohexanone

d. The given compound is formed in two ways. 

The first reaction is the addition of Gilman reagent in cyclohexanone, and then the compound formed undergoes the Wolff-Kishner reaction, where the ketone group is converted into an alkane.

The second reaction is the Wittig reaction, where the ketone group is converted to an alkene. After this, the compound formed undergoes reduction by ${\text{H}}_{\text{2}}\text{,Pd/C}$, both alkene groups present in a compound reduced to alkane.

                     Synthesis of 1-methylcyclohexane