Q32 · CSIR NET Chemistry, June 2011
Paper: CSIR NET June 2011 · Subject: Organic Chemistry · Chapter: Reagents, Reaction Mechanisms & Named Reactions · Topic: Reagents, Reaction Mechanisms & Named Reactions – General · Marks: 2 · Difficulty: Medium
The major product formed in the following transformation is: 
(a)
(b)
(c)
(d)
Answer
Answer: C ✓ checked by 4AB · confidence high
Explanation
NBS on the unsaturated acid gives bromolactonisation (cis-fused γ-lactone with Br). KOtBu then eliminates HBr to restore a ring C=C, giving the unsaturated cis-fused bicyclic lactone (c).
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