Show how each of the following compounds could be prepared fro...

Question

Show how each of the following compounds could be prepared from the given starting material. Each requires a protecting group.

b. Chemical reaction diagram showing the conversion of an alcohol to a protected alcohol using a protecting group.

Accepted Answer

All right. Hi, everyone. So first question, let's propose a synthetic approach to prepare the following compound using the given starting material. Please note that the reaction requires a protecting group. So when we go ahead and compare what's going on from start to finish, right, our starting material has both a ketone and an alcohol, right? Those are our two main functional groups. Our product, on the other hand has two alcohols and we've added an additional methyl group and that methyl group is actually where our ketone used to be, right? So we're adding carbon two a carbon that was usually or formally, I should say part of a ketone recall that that can be indicative of a green yard reagent ringed reaction, right? Because in a granu reaction, our reagent is an R group associated to a magnesium bromide group. So because the magnesium bromide has a partial positive charge, our carbon or our group that's associated to our magnesium bromide, that is going to have a partial negative charge, right. So from here, that makes the carbon nucleic, right? And so that carbon is going to go ahead and attack electro files, an example of which are carbonyl carbons, right? So this is definitely a possibility, right? We can go ahead and proceed with this plan. But one thing we have to take into consideration is the fact that our alcohol here remains untouched, right? Nothing happens to it going from start to finish. And that's interesting because recall once again, that green good reagents do in fact react with alcohols, right? They react with the hydroxy group. So the reason this question makes a point to mention that the reaction requires a protecting group is because we have to go ahead and protect the alcohol that's in our starting material, right? Because that remains untouched throughout the entire synthesis. And so we have to block any potential side reactions with our green good reagent. So our first step is actually going to be the protection of that hydroxy group because we're trying to avoid any side reactions involving it, right. So in terms of common protecting groups for alcohols, an example would be to convert our hydroxy group into a silo ether. Now, specifically, right, an example of a reaction that we can use here is t butto dimethyl silo chloride. And I know it's a lot, right? But first, we have an atom of silicone attached to an atom of chlorine, that silicone is associated to two methyl groups and a turtle group. So this right here is our chito dimethyl silo chloride. And when we react our alcohol with this molecule, we get our silo ether and recall that that is done in the presence of a base such as a, all right. So now what we're going to end up with is our silo ether. And it's important to mention that our Carboni remains untouched, right. So here the hydrogen in our O H group gets replaced by our silo group. Mhm. Mhm. So now we can go ahead and proceed with our green yard reaction, right? Because now our carbon is free and we don't have to worry about any side reactions now that our O H group has been protected, right? So because we're only adding a methyl group, our green mid reaction is going to take place with methyl magnesium bromide. Yeah, because methyl magnesium bromide has just one nucleic carbon, which is going to go ahead and attack our carbonyl carbon, right? And so that's going to force the pi electrons of our carbonyl to shift towards oxygen. And so now we get our methyl group attached, but we also end up with a negatively charged oxygen. And of course, our silo ether is still attached. So now two things need to happen, right? Number one, our O minus has to be derotated or all oxide ion I should say. And number two, our silo ether has to be removed and replaced with our hydroxy again. So this these two things, right? They can both be accomplished by adding acid to our molecule, right? Because recall that our protecting group can be removed with dilute acid. And we also need dilute acid to proton our carboxylate or sorry, our al oxide. So here after tumor with acid, right, the result is twofold because not only are we removing the protecting group, we're also proton our O minus to get an alcohol. So here we end up with two hydroxy groups in our final product, right? So just as a quick recap, our first step is always going to be protection of our alcohol, for example, to prevent any unwanted side reactions. Then now, now that we did that, in this case, we proceeded with our green good reaction at the carbon to generate our second alcohol with our additional R group attached. So with that being said, I know that was a lot, right? So if you made it to the end, thank you very much for watching. I appreciate it. And I hope you found this helpful.

Show how each of the following compounds could be prepared from the given starting material. Each requires a protecting group.
b.

Key Concepts

Protecting Groups

Synthesis of Alcohols

Reaction Mechanisms

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