ABC26OR0141 · Pericyclic Reactions
Subject: Organic Chemistry · Chapter: Pericyclic Reactions · Topic: Pericyclic Reactions – General · Exam: CSIR-NET JUNE 2011 · Marks: 2 · Difficulty: Medium
The structures of the major products X and Y in the following transformation are 
+ 
$\xrightarrow{\Delta}$ X 
Y
+ $\xrightarrow{\Delta}$ X Y(a)
(b)
(c)
(d)
Answer
Answer (as printed): C
Explanation
The product X is formed through diels alder reaction and follows the endo rule. The reaction between X and Y is the paterno-buchi reaction. The endo rule: The diels alder reaction gives bicyclic products when the diene is a ring. If the substituents on the dienophile are ‘cis’ to each other, the 2 substituents end up going down relative to the carbon bridge in the product, called the endo addition or sticking up towards the carbon bridge called the exo addition. The Diels alder reaction preferentially forms the endo product as the major product in the formed bicyclic system.