Specific Rules Governing the Diels-Alder Reaction

13 Specific Rules Governing the Diels-Alder Reaction 

Several rules govern the course of the Diels-Alder reaction. 

Rule [1 ] The diene can react only when it adopts the s-cis conformation. 

Both ends of the conjugated diene must be close to the n bond of the dienophile for reaction to occur. Thus, an acyclic diene in the i-trans conformation must rotate about the central C-C a bond to form the i-cis conformation before reaction can take place. 

This rotation is prevented in cyclic dienes. As a result  

Problem 16.18 Draw the product formed when each diene and dienophile react in a Diels-Alder reaction. 

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