Q13P - Organic Chemistry (Mcmurry)

Question

Show how you could prepare the following compounds from 4-methyl-3- penten-2-one, ${\left({\mathbf{CH}}_{\mathbf{3}}\right)}_{\mathbf{2}}\mathbf{C}\mathbf{=}{\mathbf{CHCOCH}}_{\mathbf{3}}$

(a)

(b)

(c)

Step-by-Step Solution

Answer

(a)

                                  Formation of the desired product

(b)

                                     Formation of the desired product

(c)

                                     Formation of the desired product

Step1: Starting material

The starting material is 4-methyl-3-penten-2-one which is a five-carbon chain and has a methyl group at the fourth carbon and ketone group at the second carbon and a double bond at the third carbon.

Step 2: (a) Formation of the desired product a

4-methyl-3-penton-2-one undergoes catalytic hydrogenation in the presence of $H_2/Pd$ to form the desired product which is as shown:

                                   Formation of the desired product

Step 3: (b) Formation of the desired product b

In 4-methyl-3-penton-2-one the ketone group is reduced to the methylene group by $N_2{H}_4$ and KOH. This reduction is known as wolf Kirshner reduction. The reaction is represented as:

                                   Formation of the desired product

Step 4: (c) Formation of the desired product c

4-methyl-3-penton-2-one undergoes catalytic reduction in the presence of  followed by wolf Kishner reduction using $N_2{H}_4$ and KOH reagent to form the desired product as follows:

                                      Formation of the desired product