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GATE 2026 CY – Question 38

Organic Chemistry · Pericyclic Reactions and Photochemistry: Electrocyclic, cycloaddition and sigmatropic reactions. Diels-Alder reaction, Claisen and Cope rearrangements and their applications in organic synthesis. FMO method of analysis. Woodward-Hoffmann rules. Photochemistry of alkenes, arenes and carbonyl compounds. Photo-oxidation and photo-reduction. Di-π-methane rearrangements, Norrish type-I and II reactions. Paternό-Büchi reaction, Photo- Curtius and Wolff rearrangements. Barton and Hofmann-Lӧffler-Freytag reactions. · 2 marks · Multiple choice

The correct statement about the intermediate formed in the following reaction is

Aziridine ring opening and trapping with an acetylenedicarboxylate; candidate azomethine ylides.
  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: (A) Option A in the figure

Explanation

Thermal opening of the four-electron aziridine system is conrotatory. The cis starting substituents become the in/out ester arrangement of azomethine ylide A, whose cycloaddition gives the trans ester relationship shown.

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