 So, this is the bidding reaction, let's do the mechanism. So, you have your phosphorane, remember it's an illid, right, because it prefers the resonance structure where you've got the negative charge on the carbon and the positive charge on the phosphorous. Why? Because you don't have very good pi overlap because the phosphorous is very big, carbon is very small, okay. That gives a lot of negative character, this is just one resonance structure of course. It gives a lot of negative character to that carbon, which the carbon doesn't like. And since we've got a fairly electrophilic carbon here, what we'll do with this is it's a very powerful synthetic reaction because it makes carbon carbon bonds, okay. So, anything that makes carbon carbon bonds is really cool because you can build structures, bigger and bigger organic structures, okay. So, let's just, I'm going to erase this part, okay, and we're actually going to use this resonance structure of the molecule, okay. So, I'm going to draw it in such a way. Another thing you want to know about this reaction is the driving force of this reaction is that phosphorous is very what we call oxyphilic, okay. So, it likes to be attacked by oxygen, okay. So, remember the other resonance form with the positive charge here, the negative charge here. So, we've got this dipole-dipole interaction where it's kind of inducing it to flip over this way. And then once it sees that, bam, it's going to attack, okay. But in actuality, what's going to happen is that's going to induce this double bond, of course, not only to just go up here, okay. You could show that as an intermediate, if you want. But what it really does is it goes all the way and attacks that phosphorous thing. So, you get this four-member drain. An oxyphosphatine is what they're called. So, if you want to, again, if you want to, and it helps you out, you could do the two steps, okay. In actuality, it is the more proper way to show the mechanism. But that formation there will make this phosphorous or this oxygen attack that phosphorous like that, making the oxyphosphatine. So, that's going to relieve all of those charges. But, of course, this is not a very stable structure, okay. And what it's going to do is break down, okay. This bond is going to actually break down and finish making the product. And then this one you can say does one of two things more properly goes to that oxygen and stays there. But you could also show it's making that double bond there, okay. Remember, it's the same thing when you make these phosphorous oxygen bonds where the phosphorous is much bigger than the oxygen. So, you're going to have kind of these ill structures, right. But the main thing that you're going to get out of this, and if you want to emphasize and show this two hydrogen thing. And you're also going to get triphenol. Are there any questions from this one? So, I think they call this structure the B-team structure. And this is the one more important, the oxyphosphatine. So, again, this is a cool synthesis because you can take a ketone or aldehyde.