Q16 · CSIR NET Chemistry, December 2015
Paper: CSIR NET December 2015 · 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 reaction sequence is: 
(a)
(b)
(c)
(d)
Answer
Answer: D ✓ checked by 4AB · confidence medium
Explanation
PhSeCl on 1,5-cyclooctadiene triggers transannular cyclisation: the episelenonium ion is captured by the second alkene and acetate traps the cation, giving the cis-bicyclo[3.3.0]octane acetoxy-selenide; H₂O₂ oxidation and selenoxide syn-elimination give the acetoxy-bicyclo[3.3.0]octene (d).
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