Q125 · CSIR NET Chemistry, December 2011
Paper: CSIR NET December 2011 · Subject: Organic Chemistry · Chapter: Pericyclic Reactions · Topic: Pericyclic Reactions – General · Marks: 2 · Difficulty: Medium
The major products A and B in the following reaction sequence are 
$\xrightarrow{\Delta}$ (A) 
(B)
$\xrightarrow{\Delta}$ (A) (B)(a)A = 
B = 
B = (b)A = 
B = 
B = (c)A = 
B = 
B = (d)A = 
B = 
B = Answer
Answer: B ✓ checked by 4AB · confidence medium
Explanation
Conrotatory thermal opening of trans-dimethylbenzocyclobutene gives the (E,E)-o-xylylene, with both methyls outward. Suprafacial Diels–Alder with maleic anhydride then places the two methyls cis in B (b).
Study loop for Pericyclic Reactions