Question

Question: Draw a stepwise mechanism for the following reaction. This reaction combines two processes together: the opening of an epoxide ring with a nucleophile and the addition of an electrophile to a carbon–carbon double bond. (Hint: Begin the mechanism by protonating the epoxide ring.)

Short answer

Answer

Step-by-step solution

Ring-opening of epoxide

Ring-opening of an epoxide is completed by nucleophiles or Lewis bases in acidic and basic mediums.

In the basic medium, the epoxide gives a more substituted alcohol, and in the acidic medium, it gives a less substituted alcohol.

Addition of an electrophile

The addition of an electrophile gives the electron-vacant position where a nucleophile attacks and forms the desired product.

Explanation

The mechanism of intramolecular ring-opening in the acidic medium gives a less substituted alcohol. Ring-opening is completed by the alkene nucleophile.

The attack of alkene generates a carbocation that is attacked by the water molecule.

The mechanism is shown below:

Reaction of epoxide