Since this reaction always passes through an anion intermediate, we can actually use activating groups and deactivating groups to direct the site of the isolated diene. How does that work? Let's just take a look at the anion or the carbanion intermediate. This would be the point where we have the 2 double bonds. We have the 2 H's and we have a lone pair negative at the top.

Let me ask you a question. If I add an electron withdrawing group to that anion? What do you think it does for stability? Do you think it makes that anion more stable or less stable? Hold that thought. What happens if I add an electron donating group to that anion? What if I add something that's going to give more electrons to the negative? What does that do for the stability? The answer is that the first one is going to make it more stable because it pulls electrons away. An electron donating group is actually going to make it less stable because it's going to push more electrons into the anion.

It turns out that these different groups are going to direct where the double bonds go. As you guys can see, withdrawing groups are going to what I say isolate themselves from the diene. I specifically chose that word for a reason because withdrawing and isolate kind of mean the same thing. If you're withdrawing from the crowd, that means you're isolating yourself. A withdrawing group is going to be isolated from the double bond. It's going to be away from the double bond. And why is that? It's not just because we memorized it. It's because you know that it's going to stabilize the negative charge. It's going to want to be where the negative charge was.

Whereas donating groups are going to attach themselves directly to the diene like in this situation. Why? Because I have electrons going into the ring and I don't want it to be here. Because if it was there, it would make my anion less stable. I'm trying to put it in a place where it's not going to affect the stability, where it's going to be fine. Electron donating groups attach to the ring and withdrawing groups isolate from the ring. If you don't remember the mechanism, you can at least remember the way that I'm telling you which is that withdrawing isolates. You can think of just isolating yourself from the crowd, you're withdrawing or donating attaches which is basically the opposite.

Awesome, guys. So really that's it for this topic. Let's move on to the next one.