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GATE 2026 CY – Question 14

Organic Chemistry · Reduction: Catalytic homogeneous and heterogeneous hydrogenation. Metal based reductions using Li/Na in liquid ammonia, magnesium, zinc, titanium, and samarium. Hydride transfer reagents: NaBH4, L-selectride, K-selectride, Luche reduction, LiAlH4 and DIBAL-H. · 1 mark · Multiple choice

The major product formed in the following reaction is

Cyclopentanone tethered to an unsaturated ester treated with SmI2, THF, then methanol.
  1. Option A in the figure
  2. Option B in the figure
  3. Option C in the figure
  4. Option D in the figure

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Correct answer: (B) Option B in the figure

Explanation

Single-electron reduction forms a ketyl radical which attacks the beta carbon of the tethered unsaturated ester by favorable 5-exo cyclization. Reduction and protonation give the fused five-membered alcohol B.