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Topic: Electrocyclic Ring Closure Confusion  (Read 1356 times)

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Offline robertosin

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Electrocyclic Ring Closure Confusion
« on: October 02, 2018, 11:41:07 PM »
Hi all.

I know the molecule is [4n+2]. Under heat, it should have disrotatory motion and under light, conrotatory. I am having trouble seeing the final products. Any insights on how to approach this problem and similar complex ring scenarios.

The molecule: https://imgur.com/a/ktfBeFp


Offline pgk

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Re: Electrocyclic Ring Closure Confusion
« Reply #1 on: October 04, 2018, 11:20:01 AM »
1). Draw the product of the intramolecular Diels-Alder reaction.
2). Draw the new formed, six member ring (or all the rings, if you prefer) of that product, as a chair conformer.
3). This will help you to distinguish the conrotary and the disrotary final product.
4). Re-draw the conrotary and disrotary final products in planar form and draw the methyl group and the ipso-hydrogen above or below the plane, as concluded by their chair conformation.
PS: Ipso-hydrogen is the hydrogen bonded with the same carbon atom as the methyl group.

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