Alright, so here are 2 products of Claisen rearrangements. Now you're going to have to kind of trust me on that because we didn't go through the whole mechanism, but just take my word for it that these are the products of the Claisen rearrangement, which actually is the product we just did, and then this is another Claisen rearrangement, okay? So just take my word for it that these are two products of Claisen rearrangements. Now we need to do, I shouldn't have circled; that's a good thing about having eraser. What we have to do is pick the more stable tautomer of the 2 using what we know about keto-enol tautomerism. Now if you're confused about this or if this isn't too clear to you, I have a whole series of videos on picking the most stable tautomers in tautomerization. So you can just search in the search bar of YouTube for Claisen tautomerization and you're going to get more information on this. This is just a quick review and remember that, so let's just look at the first one, we'll do both of them side by side. So the first one, this is my keto and this is my enol, right? Which one is favored in this case? So guys, just so you know, the rule is that the keto is pretty much always favored. So I'm going to go ahead and circle it. We're done. You would not tautomerize this one. Cool. What about this equilibrium here? I'm going to step outside so you can see both clearly. What I see is that here once again I have a keto and here I have an enol.
Now, out of these 2, which one is more favored? Guys, there are only 2 examples in which the enol is more favored, and I'm going to give them to you here. One is when you can make an aromatic product or an aromatic enol, and two is when you have a beta-dicarbonyl enol. Okay? These are the 2 situations in which enols are actually more favored. If you have it, if either you can make it aromatic or if it's in the form of beta-dicarbonyl, and I do go over both of these situations in my tautomerization videos. So, what do we have here? Do we have any of those 2 situations? Yes, we do, because notice that our first molecule is not aromatic. Aromatic just means that it has alternating single and double bonds, which is going to make it more stable, like our clutch loop, like a benzene ring. So this one does not look like a benzene ring, it's not aromatic, but this one has a benzene ring. It's actually phenyl, this specific enol is called phenyl. So if you have a choice between non-aromatic and aromatic, we pick this one. It turns out that this molecule, if you do not tautomerize to the phenyl, you get the question wrong.
So this is one specific situation or one of 2 situations that you have to make sure that you tautomerize to the enol if it's stable, if it's more stable, but the other one, you could just leave as keto. Does that make sense? This is just to do with the guys; this has to do with the fact that we're using oxygen now and oxygen has the ability to either form an alcohol or either form a carbonyl. So that's why you have to think about this step with a Claisen rearrangement, okay. Awesome. So let's move on to the next video.