In order for a Diels-Alder reaction to take place the diene must be in what
conformation?
A. cis
B. trans
C. s-trans
D. anti
E. s-cis
To determine the correct conformation for a Diels-Alder reaction to take place, we need to understand the requirements of the reaction.
In a Diels-Alder reaction, a diene and a dienophile participate in a concerted reaction to form a cyclic compound called a cycloadduct. The diene must have two double bonds separated by a single bond, also known as a conjugated system.
For the reaction to occur, the diene must adopt the s-cis conformation. In the s-cis conformation, the substituents on the double bonds are oriented in the same plane, making them aligned and available for the reaction. It is important to note that the diene should not be in a twisted conformation, as this would hinder the reaction.
Therefore, the correct answer is E. s-cis.