Q39E
Question
The following reaction is an example of a [2,3] sigmatropic rearrangement. Would you expect the reaction to be suprafacial or antarafacial? Explain.
Step-by-Step Solution
Verified Answer
A [2,3] sigmatropic rearrangement involves three electron pairs (one π bond, one lone pair, and one σ bond), the orbital-symmetry rules predict a suprafacial reaction
1Step 1: Orbital-symmetry rules
A [2,3] sigmatropic rearrangement involves three electron pairs (one π bond, one lone pair, and one σ bond), the orbital-symmetry rules predict a suprafacial reaction.
According to the rules
Electron pairs (double bonds) | Thermal reaction | Photochemical reaction
|
Even number | Antarafacial | Suprafacial |
Odd number | Suprafacial | Antarafacial |
2Step 2: Mechanism
The mechanism for [2,3] sigmatropic rearrangement is shown as:
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