Reaction of m-menthylanisole with lithium in liquid ammonia and t-butyl alcohol at –33°C generates compound X… · ABC26OR0542
Subject: Organic Chemistry · Chapter: Organic Synthesis · Topic: Organic Synthesis – General · Exam: GATE 2000-2022 · Marks: 2 · Difficulty: Medium
Reaction of m-menthylanisole with lithium in liquid ammonia and t-butyl alcohol at –33°C generates compound X as the major product. Treatment of the compound X with dilute sulphuric acid produces compound Y as the major product. The compounds X and Y, respectively, are
(a)
and 
and (b)
and 
and (c)
and 
and (d)
and 
and Answer
Answer (as printed): D
Explanation
Birch reduction (Li/liq. NH₃, t-BuOH) of m-methylanisole leaves both electron-donating groups (OMe and Me) on the remaining double bonds: X = 1-methoxy-5-methylcyclohexa-1,4-diene (the X drawn in (c)/(d)). Dilute H₂SO₄ hydrolyses the enol ether to the β,γ-unsaturated ketone, which isomerises under acid into conjugation: Y = 3-methylcyclohex-2-en-1-one. Answer: (d).
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