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GATE 2022 CY – Question 38

Organic Chemistry · Types of Reactions: Nucleophilic and electrophilic substitution reactions (both aromatic and aliphatic). Addition reactions to carbon-carbon and carbon-heteroatom (N and O) multiple bonds. Elimination reactions. Reactive intermediates – carbocation, carbanion, carbenes, nitrenes, arynes and free radicals. Molecular rearrangements. Barton decarboxylation and Barton-McCombie reaction, Hunsdiecker reaction. · 2 marks · Multiple choice

The major product P in the following reaction is

Diagram for GATE 2022 CY question 38
  1. Diagram A
  2. Diagram B
  3. Diagram C
  4. Diagram D

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Show answer and explanation

Correct answer: (A) Diagram A

Explanation

Fluoride generates benzyne from the adjacent silyl/triflate precursor. Addition of theβ-ketoester enolate gives an aryl anion that undergoes acyl transfer through a cyclic intermediate. Net insertion into the acyl–α-carbon bond separates the acetyl and CH2CO2Me groups onto adjacent aryl positions. This ring-expanded connectivity is **A**.