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GATE 2023 CY – Question 37

Organic Chemistry · Heterocyclic Compounds: Nomenclature of mono- and bicyclic, as well as mono- and di-heteroatomic compounds, Structure, preparation, properties and reactions of furan, pyrrole, thiophene, pyridine, indole, quinoline and isoquinoline. · 2 marks · Multiple choice

The major product formed in the given reaction sequence is

Diagram for GATE 2023 CY question 37
  1. Structure A
  2. Structure B
  3. Structure C
  4. Structure D

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Show answer and explanation

Correct answer: (B) Structure B

Explanation

First, N-alkylation replaces bromide and attaches the phenacyl chain to phthalimide nitrogen. Base then forms the ketone enolate, which attacks an adjacent imide carbonyl and undergoes Gabriel–Colman ring expansion. The resulting isoquinoline skeleton retains benzoyl at C4 and OH at C1/C3, selecting **B**, not the quinoline isomer A.