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GATE 2022 CY – Question 15

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. · 1 mark · Multiple choice

The major product M in the following reaction is

Diagram for GATE 2022 CY question 15
  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

The di-π-methane rearrangement joins the diene ends through a biradical and gives a vinylcyclopropane. The favoured path places the electron-withdrawing aryl groups on the cyclopropane carbon while retaining the diphenyl-substituted vinyl terminus. The original gem-dimethyl central carbon remains a ring carbon, matching **A**, not D.