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3. Draw the structure of the major organic product that forms in each of the following reactions Specify stereochemistry where appropriate.
a)
$\xrightarrow[ ext { 2) } \mathrm{CH}_{5} \mathrm{P}]{ ext { 1) } \mathrm{Ph}_{3} \mathrm{CNa} / ext { Ether }}$
b)
c)
1) DIBAL(excess)
$-78^{\circ} \mathrm{C}=\mathrm{H} / 3^{\circ}$
2.) $\mathrm{MnO}_{2} / \mathrm{CH}_{2} \mathrm{Cl}_{2}$ $\mathrm{N} / 3$

Question

-3 -
3. Draw the structure of the major organic product that forms in each of the following reactions Specify stereochemistry where appropriate.
a)
$\xrightarrow[	ext { 2) } \mathrm{CH}_{5} \mathrm{P}]{	ext { 1) } \mathrm{Ph}_{3} \mathrm{CNa} / 	ext { Ether }}$
b)
c)
1) DIBAL(excess)
$-78^{\circ} \mathrm{C}=\mathrm{H} / 3^{\circ}$
2.) $\mathrm{MnO}_{2} / \mathrm{CH}_{2} \mathrm{Cl}_{2}$ $\mathrm{N} / 3$

Accepted Answer

∻Solution∻ ‖ 1 ⋮ **Identify the reagents and reaction conditions for part a)**: The reagents $\mathrm{Ph}_{3}\mathrm{CNa}$ and $\mathrm{CH}_{5}\mathrm{P}$ suggest a Wittig reaction, which is used to form alkenes from carbonyl compounds. ‖ ‖ 2 ⋮ **Predict the product for part a)**: The Wittig reaction typically yields an alkene. The stereochemistry of the product depends on the ylide used, but with $\mathrm{Ph}_{3}\mathrm{CNa}$, we would expect the formation of a trans-alkene as the major product, assuming the starting material is a carbonyl compound. ‖ ∻Answer∻ ⚹ The major organic product for part a) is a trans-alkene formed from the reaction of a carbonyl compound with $\mathrm{Ph}_{3}\mathrm{CNa}$ and $\mathrm{CH}_{5}\mathrm{P}$. ⚹ ∻Key Concept∻ ⚹ Wittig Reaction ⚹ ∻Explanation∻ ⚹ The Wittig reaction converts carbonyl compounds to alkenes using a phosphonium ylide, often leading to trans-alkenes. ⚹ ∻Solution∻ ‖ 1 ⋮ **Identify the reagents and reaction conditions for part c)**: DIBAL (Diisobutylaluminum hydride) is a reducing agent that is often used to reduce esters to aldehydes selectively. The reaction is performed at $-78^{\circ}\mathrm{C}$ to prevent further reduction. $\mathrm{MnO}_{2}$ is a mild oxidizing agent that can oxidize primary alcohols to aldehydes without affecting other functional groups. ‖ ‖ 2 ⋮ **Predict the product for part c)**: The first step with DIBAL would reduce an ester to an aldehyde. The second step with $\mathrm{MnO}_{2}$ would not further oxidize the aldehyde since $\mathrm{MnO}_{2}$ is not strong enough to oxidize aldehydes to carboxylic acids. ‖ ∻Answer∻ ⚹ The major organic product for part c) is an aldehyde, which is the result of the selective reduction of an ester by DIBAL, followed by no further reaction with $\mathrm{MnO}_{2}$. ⚹ ∻Key Concept∻ ⚹ Selective Reduction and Mild Oxidation ⚹ ∻Explanation∻ ⚹ DIBAL selectively reduces esters to aldehydes at low temperatures, and $\mathrm{MnO}_{2}$ is a mild oxidant that can oxidize primary alcohols to aldehydes but does not affect aldehydes. ⚹ (Note: The student did not provide a specific starting material for the reactions, so the answers are based on typical outcomes for the given reagents and conditions.)◊What is the role of DIBAL in the given reaction?⍭ Generate me a similar question◊

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