Q18 · CSIR NET Chemistry, June 2018
Paper: CSIR NET June 2018 · Subject: Organic Chemistry · Chapter: Reagents, Reaction Mechanisms & Named Reactions · Topic: Reagents, Reaction Mechanisms & Named Reactions – General · Marks: 2 · Difficulty: Medium
Structure of the intermediate A and the final product B in the following reaction sequence are 
$\mathrm{A}$ 
$\mathrm{CH_2Cl_2}$, $0^{\circ}\mathrm{C}$ $\mathrm{B}$
$\mathrm{A}$ $\mathrm{CH_2Cl_2}$, $0^{\circ}\mathrm{C}$ $\mathrm{B}$(a)$\mathrm{A}=$ 
$\mathrm{B}=$ 
$\mathrm{B}=$ (b)$\mathrm{A}=$ 
$\mathrm{B}=$ 
$\mathrm{B}=$ (c)$\mathrm{A}=$ 
$\mathrm{B}=$ 
$\mathrm{B}=$ (d)$\mathrm{A}=$ 
$\mathrm{B}=$ 
$\mathrm{B}=$ Answer
Answer: A ✓ checked by 4AB · confidence medium
Explanation
Pd(0) opens the vinyl epoxide to a π-allyl with the alkoxide anti to Pd; the malonate attacks anti to Pd, so nucleophile and OH end up cis (A). m-CPBA is then directed by the free hydroxyl to the syn face, giving the epoxide cis to OH (B) — (a).
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