Identify the major product P and Q in the following reactions from the list of compounds I to IV. I II III IV · ABC26OR0559
Subject: Organic Chemistry · Chapter: Pericyclic Reactions · Topic: Pericyclic Reactions – General · Exam: GATE 2000-2022 · Marks: 2 · Difficulty: Medium
Identify the major product P and Q in the following reactions from the list of compounds I to IV. 
I 
II 
III 
IV
I II III IV(a)P:I and Q:II
(b)P:II and Q:III
(c)P:IV and Q:II
(d)P:IV and Q:III
Answer
Answer: B ✓ checked by 4AB · confidence medium
The source book printed C; on checking, B is correct — see the explanation.
Explanation
Acetophenone (high triplet energy) sensitises the [2+2] photodimerisation of norbornene, giving the exo-trans-exo dimer (II); benzophenone instead undergoes Paternò–Büchi with the alkene to give the oxetane III — (b).
Study loop for Pericyclic Reactions