Comments on: Regiochemistry In The Diels-Alder Reaction

By: James Ashenhurst

James Ashenhurst — Mon, 29 Jul 2024 21:55:07 +0000

In reply to Mu Hsuan-Jung. Very glad you are finding the website helpful! Thank you!

By: Mu Hsuan-Jung

Mu Hsuan-Jung — Thu, 25 Jul 2024 14:08:41 +0000

This website is so darn helpful!!! I’m an undergrad in Taiwan and I’m organizing my notes in organic chemistry recently. I want to analyze the stereochemistry and regioselectivity of all the reactions, which our instructor didn’t introduce to us in the case of Diels-Alder reaction. Since I’m not majoring in chemistry but in medical science, this website really helps me get to know so many details which I couldn’t have learnt from my textbooks and even in lectures. Thank you so much sir!

By: Sourav

Sourav — Sat, 03 Jul 2021 05:19:37 +0000

Is there an answer to the question by JM yet?

By: James Ashenhurst

James Ashenhurst — Fri, 16 Oct 2020 19:51:27 +0000

In reply to Andy. It *is* supposed to be ortho: meta. Thanks for the spot! Fixed

By: Andy

Andy — Mon, 31 Aug 2020 05:11:25 +0000

Hi James, this website has been a tremendous help for actually understanding (and not just regurgitating) organic chemistry, so thank you so much for that! I just noticed that, in the “Case 1: 1-substituted dienes” section, the fourth dot point mentions an 8:1 ratio between ortho and para, however the subsequent image shows an 8:1 ratio between ortho and meta. Is there also an ortho:para relationship here, or is the dot point supposed to be ortho:meta? Thank you again!

By: James Ashenhurst

James Ashenhurst — Wed, 11 Mar 2020 21:47:00 +0000

In reply to JM. That is a great question. Methoxy is a more powerful directing group than methyl, but directing groups on the 1-position are more dominant than directing groups on the 2-position. I will have to look it up. Thanks for asking.

By: JM

JM — Mon, 24 Feb 2020 15:54:41 +0000

First of all this entire website has been so helpful, thank you so much for helping clarify all these confusing concepts!
In your example of the 1,2 disubstituted diene you have 2 identical substituents. What would happen in the reaction if you had a 1,2 disubstituted diene with different substituents (say, for example, a methyl on position 1 and methoxy on position 2)? Is one substituent more “powerful” than the other and therefore more influential in determining the final Diels-Alder product, even though the position 1 substituent is the one that determines the final structure like you said? I read online that methoxy is a more powerful directing group than methyl. Not sure how true that is or if it’s relevant to this. Thank you!

By: James

James — Tue, 05 Feb 2019 17:58:49 +0000

In reply to Cassani. Good question! The result will still be "ortho" and "para" products. If you start adding electron withdrawing groups to the diene, then it will tend to undergo inverse electron-demand diels alder reactions (i.e reacting with electron rich "dienophiles"). So something like 2-cyanobutadiene will react with ethyl vinyl ether, but still give para, not meta!

By: Cassani

Cassani — Tue, 20 Nov 2018 19:19:04 +0000

Hi, quick question. In regards to ‘1-substituted dienes’ and ‘2-substituted dienes’ can electron withdrawing groups vs electron donating groups affect the ‘head:head or head:tail’ alignments and therefore break the given rule that a ‘1-substituted diene’ always gives ortho product?