Q49 · CSIR-NET Chemistry, June 2017
Paper: CSIR-NET June 2017 · Subject: Organic Chemistry · Chapter: Pericyclic Reactions · Topic: Cycloaddition Diels Alder · Marks: 2 · Difficulty: Medium
Following reaction is an example of 
(a)$[3+2]$ cycloaddition
(b)[4 + 2] cycloaddition
(c)[6 + 2] cycloaddition
(d)$[8+2]$ cycloaddition
Answer
Answer: D ✓ checked by 4AB · confidence medium
Explanation
The 7-substituted cycloheptatriene (via its 8π heptafulvene-type system) adds TCNE across the ring carbon and the exocyclic carbon. This forms a five-membered ring: an [8+2] cycloaddition (d).
Study loop for Pericyclic Reactions