Q76 · CSIR NET Chemistry, December 2016
Paper: CSIR NET December 2016 · Subject: Organic Chemistry · Chapter: Photochemical Reactions · Topic: Photocycloaddition · Marks: 2 · Difficulty: Medium
The major product formed in the following reaction is 
(a)
(b)
(c)
(d)
Answer
Answer: A ✓ checked by 4AB · confidence medium
Explanation
Barton reaction: hν cleaves O–NO, and the alkoxyl radical abstracts a δ-H (1,5-H shift) from the neighbouring CH₂ of the spiro cyclopentane. NO recombines to give an oxime, which H₃O⁺ hydrolyses to the ketone. The alcohol is regenerated (a).
Study loop for Photochemical Reactions