Question: Devise a synthesis of X from the given starting materials. You may use any organic or inorganic reagents. Account for the stereochemistry observed in X.

The Diels-Alder reaction occurs when a diene (conjugated diene) reacts with an alkene. The reaction may form exo or endo products.

The endo product is formed towards the cavity and the exo is formed above the cavity.

The stereochemistry of the Diels-Alder product is determined by the orientation of groups. For example, the outside groups have cis stereochemistry.

The given product is formed by the Diels-Alder reaction followed by the ozonolysis reaction in the presence of reducing agents.

Here, both methyl groups are on the same side. Therefore, it is a cis product. The stereochemistry of hydrogen in the endo product is above the plane as the reaction is towards the cavity.

The reaction scheme is shown below:

Diels-Alder reaction