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GATE 2023 CY – Question 48

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. · 2 marks · Multiple select

Product(s) formed in the reaction below is(are)

Diagram for GATE 2023 CY question 48
  1. Structure A
  2. Structure B
  3. Structure C
  4. Structure D

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Show answer and explanation

Correct answer: (A) Structure A; (C) Structure C

Explanation

Tin in acid reduces the isoquinoline nitrogen-containing ring, forming tetrahydropapaverine **A**. Acidic iminium chemistry can additionally give intramolecular aryl capture and reduction to the bridged pavine skeleton **C**. B/D connect the benzyl aromatic ring to the wrong positions for the allowed reductive cyclization. Both A, C are accepted products.