In the following reaction sequence, the major products Q and R are: · ABC26OR0614
Subject: Organic Chemistry · Chapter: Reagents, Reaction Mechanisms & Named Reactions · Topic: Reagents, Reaction Mechanisms & Named Reactions – General · Exam: GATE 2000-2022 · Marks: 2 · Difficulty: Medium
In the following reaction sequence, the major products Q and R are: 
(a)
Q and 
R
Q and R(b)
Q and 
R
Q and R(c)
and 
and (d)
and 
and Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed B; on checking, C is correct — see the explanation.
Explanation
Sonogashira/TBAF gives 4-methylphenylacetylene; catecholborane and hydrolysis give the (E)-vinylboronic acid P. NaOH/I₂ iodinates with retention → (E)-vinyl iodide Q; Br₂ then NaOMe (anti bromination, anti deboronobromination) gives the (Z)-vinyl bromide R — (c).
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