Q20 · CSIR NET Chemistry, December 2014
Paper: CSIR NET December 2014 · Subject: Organic Chemistry · Chapter: Reagents, Reaction Mechanisms & Named Reactions · Topic: Named Reactions · Marks: 2 · Difficulty: Medium
The major product of the following reaction is:
\[ \begin{array}{l} 1. \text{Methoxybenzaldehyde, }\mathrm{H^{+}} \\ 2. \text{DIBAL-H, -78 to }40^{\circ}\mathrm{C} \end{array} \]
(a)
(b)
(c)
(d)
Answer
Answer: A ✓ checked by 4AB · confidence medium
Explanation
p-Anisaldehyde forms the 1,3-dioxane (PMP acetal) across the 1,3-diol; DIBAL-H opens it regioselectively, delivering hydride via the less hindered oxygen so that the PMB ether ends up on the secondary alcohol and the primary OH is freed (a).
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