 Okay. So let's try this reaction. It's also chloride and pyridine reacting with an alcohol. So when we do this reaction, what's the reason we're doing it for? We want to make an alkene. No. Alkone going to the good leaving group. We want to take a what? Alkone. Bad leaving group and do what? And we're going to do a better leaving group. Right? Not only a better leaving group, the what? The best one. The best one that we know, right? I think we've been over that before, right? Yes. Those are wonderful. So in order to do this vanquanism, what's the product of this reaction? Can you draw it? Everybody draw it first. Is that what you wrote? Put the wedge. Why is that important? Because we've got to identify our stereochemistry. So what if we wanted to do an SN2 reaction on this substrate? We can't do it, right? Why is that again? Because the OH is a bad leaving group. So if we have this substrate, can we do the SN2 reaction on it? Yes. That's what we're talking about, okay? Everybody's okay with that, right? Okay, cool. So now we're going to do the mechanism of this reaction. Okay? In order to do a mechanism, like we said, so I've already showed you once before, okay? But like we said before, if you don't know the molecular structure of tussle chloride or pyridine, right? You're not going to be able to do this mechanism, okay? So make sure you're able to remember those two structures. I want you to draw them right now. And since I'm doing the mechanism, I'm going to erase this and I'm going to draw some electrons and bonds over here. Okay, so pyridine, everybody should know by now, tussle chloride, that's a little harder to remember, but something you definitely want to. Did everybody draw those two things? Yes. Okay, wonderful. So the pyridine actually comes in a little bit later, so I'm going to erase that as well, okay? Remember that it's there. And let's put some electrons here. Okay, so what's going to happen first? The oxygen is going to attack this sulfur, which is actually electrophilic, okay? The sulfur actually has a pretty high, partially positive charge on it, which you might not expect from that structure, but if you think about resonance structures, right, you would expect that the electrons would go to the oxygens, right, in a resonance structure. And that's actually kind of what we're about to show is that these electrons are going to attack the sulfur. And why don't we just say the electrons for the double bond are going to go up to the oxygens. So I want you to draw that product from that reaction. So remember, did you draw something like that? Yes. So now what we're going to do is take these electrons, make the double bond again, and kick off that chlorine as a good leaving group. So now I want you to draw the product of that mechanism. Just do your best, okay? Now we have this. Let's put our electrons. And then, of course, the C l minus got kicked off like that. Okay, now the pyridine comes in. Pyridine is a base, right? So what is the base going to do in this step? It's going to deprotonate. Deprotonate, okay? So do you see the acidic proton? The one on the oxygen. The oxygen, deprotonated, like that. So we also have what we've done there. And then this thing here is just TOS, okay? It's just TOS. So I'm going to just draw it down here, and hopefully you can still see it on the video. S-O-T-O-S, okay? Is everybody okay with what we've done in this mechanism? Yes. Yeah, yes. Okay. So hopefully this makes more sense than when we learned it the first time. Is everybody okay with that? Is there any questions on this? Please feel free to ask any questions now. Any questions. If you don't have any, that's fine too. Why is the chlorine going to the same... To where? So this arrow here, why is it going to the chlorine? Because the chlorine's leaving it. Okay, you're kicking off that chlorine. Because the oxygen has those electrons kicking off, right? Yeah, the oxygen's coming back down, right? And sulfur, it can't make that many bonds, right? So once you make that double bond again, it's got to kick off the chlorine. Gotcha. Professor, would you include what the puramine derivative, the M plus in the major organic products? I wouldn't put it in there now. They're talking, if it says major organic, they're talking about this, okay? And if they do... It is an organic, what do you say? It's in the organic mixture, you're absolutely right. And it's an organic molecule, but you wouldn't consider it an organic product. You would say that this is like the byproducts of the reagents. Okay, byproducts. Yeah. Because that's not what you're interested in, right? Right. You're interested in the tosylate. Gotcha. That makes sense. Any other questions? Okay, cool. Kill.