Now let's talk about a synthetic application of a settles, and that's to use a settles as protecting groups. So let's look at these two molecules above me, and what we'll find is that these molecules are in equilibrium. Okay, we have learned that if you expose ah, carbon heel, toe, alcohol and acid, you can basically Macon asked How? Okay, So in this case, since there's a cyclic a subtle I would expect to be using a cyclic dial's in combination with acid. So I just put h plus to give me my sick. Like I said, Tell okay, what's important about the difference between these is that there's a huge difference in reactivity between my original carbon eel and my ass. Little notice that my carbon eel has an extremely reactive, partial positive pylon, right, whereas in a Seattle does have die polls. So it does have die polls similar to the carbon Neil, but notice that they're located on Sigma bonds, not on a pie bond. So all these bonds are extremely difficult to break. In fact, in a Seattle is about as reactive as an ether. Just remember how reactive ethers were pretty much un reactive ethers barely do anything. All you could do is combust them Sure they blow up, but other than combustion, they don't react. That's because thes single bonds are extremely difficult to break. So now if I asked you which one is the safer version if I was to run a reaction somewhere else on the molecule, which one is safer toe, have around a carbon ill or has to tell? And the answer is in a settle because a subtle really isn't going to react with almost anything. Okay, whereas a carbon eel is so reactive, we've learned it can even wrecked with water, so we want to protect it. And that's the whole idea behind a protecting group. So assets house are used to protect sensitive Alba highs and key tones from reaction with other agents since they're reversible. The idea being that you can turn the Carbonell in to an acquittal, do your reaction somewhere else, and when you're done, you can go ahead and hide, relies it back to the original carbon eel, sparing it from reaction with your second re agent. So I want you guys to look at this example, and I want you guys to devise a synthesis for this. I want you toe look at these two molecules and figure out what would be the best way to make that first molecules into the second one. Now I'm gonna give you a hint. This is not a one step reaction. If you try to do it in one step, you're gonna fail. So try to think about what reactions you could do in what sequence to make this transformation happen, and then I'll show you.