Q.30-6 - Organic Chemistry (Mcmurry)

Question

1,3-Cyclopentadiene reacts with cycloheptatrienone to give the productshown. Tell what kind of reaction is involved, and explain the observed result.Is the reaction suprafacial or antarafacial?

Step-by-Step Solution

Answer

The reaction is (6+4) II cycloaddition reaction. The resultant reaction is suprafacial cycloaddition reaction.

The formation of the final product.

Upon reaction of 1,3-Cyclopentadiene with cycloheptatrienone will give the following product given below:

Mechanism:

It uses two of its pi electrons in the reaction of 2,4,6-cycloheptatrienone with cyclopentadiene.

On the other hand, if 2,4,6-cycloheptatrienone reacts with ethene, then it will use four of its pi-electrons because ethene is the two pi-electron reactants.

The kind of reaction involved.

Both the reaction involves [4+2] cycloaddition reactions. It uses two of its pi electrons in the reaction of 2,4,6-cycloheptatrienone with cyclopentadiene. This is because cyclopentadiene is the four pi-electron reactants.

On the other hand, if 2,4,6-cycloheptatrienone reacts with ethene, then it will use four of its pi-electrons because ethene is the two pi-electron reactants.