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GATE 2026 CY – Question 36

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 formed in the following reaction is

Gem-dimethyl bicyclic chair alcohol treated with acid and four rearranged alkenes.
  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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Show answer and explanation

Correct answer: (B) Option B in the figure

Explanation

Loss of water forms a tertiary cation. The antiperiplanar ring bond migrates in a Wagner–Meerwein contraction; elimination gives the more substituted exocyclic isopropylidene alkene B.

Official GATE 2026 answer key: https://gate2026.iitg.ac.in/doc/download/2026/Keys/CY_Keys.pdf