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GATE 2021 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 formed in the following reaction is:

Diagram for GATE 2021 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

NOCl converts the alcohol into its nitrite ester. Photolysis cleaves the O–N bond to an alkoxy radical, which abstracts a spatially accessible remote hydrogen through a six-membered transition arrangement: the Barton nitrite reaction. Capture by NO forms a nitroso intermediate, which tautomerizes to an oxime; acidic hydrolysis gives the aldehyde. The suitably positioned methyl group becomes CHO while the alcohol is regenerated, giving **A**.