Question

Draw the intermediate and final organic structures in the following two-step reaction, showing the correct stereochemistry.

Answer 1

Concepts and reason

The problem is based on the concept of epoxide ring opening in the presence of a base. In basic medium, epoxide undergo ring opening via ${S_{\rm{N}}}2$ mechanism.

Fundamentals

Epoxides are three-membered ring structures which contain an oxygen atom at one vertex and two carbon atoms at other two vertices. The carbon atoms in epoxides ring are electrophilic and therefore, react with nucleophile which opens the strained ring.

An example of ring-opening of symmetrical epoxide is as follows:

In case of unsymmetrical epoxide ring, the nucleophile attacks from the less hindered side. An example of ring-opening of unsymmetrical epoxide is as follows:

The mechanism of the ring opening reaction is as follows:

The reaction mechanism is as follows:

Ans:

The intermediate formed in the reaction is,

The final product of the reaction is,