Identify A through O:

Question

Diagram illustrating a series of radical reactions with labeled steps A through O, showing chemical transformations and reagents.

Accepted Answer

All right. Hi, everyone. So first question, let's go ahead and identify the missing products. So here we have two reactions and we have to come up with the products A and B with our starting material being one methyl cyclo. So with that being said, let's go ahead and focus our attention on each individual reaction, right? Starting off with product A right? Or reaction A. So what's happening here is that like I mentioned before, we have an alcohol, right? We have one methyl Cyclo entin and we're reacting it with H B R, right? So recall that O H groups are not very good leaving groups, right, in the context of nucleic substitution. So there are a couple of modifications that you can make to an O H group in order to force it, so to speak, right? To make it a better lead group, one such method is proton it, right? Because when you proton an O H group and the leaving group leaves, you end up with a molecule of water. So here what's happening is that we are adding H pr to an O H group which of course is a strong acid, right? So that means that this is going to be a substitution because the H pr is going to ate this O H group here and make it a better living group, right? Which makes it a lot easier for bro to go ahead and substitute our O H group on the ring. So in this case, right, this is going to be a substitution reaction. So we know that our O H group is going to be replaced by the bromine coming from H B R in product A, right? So now we end up with an A bromide and we can go ahead and proceed with reaction B here, but there's a lot happening in reaction B, right? So I want to go ahead and take it step by step starting with our product A at the bottom here. So I'm going to start by drawing our starting material or our intermediate, I should say. And I'm going to go ahead and illustrate how each step changes the structure of our intermediate. Now, what I'd like to draw to your attention is the fact that our first two steps involve the introduction of lithium and copper right now, this looks a little familiar, right? Because recall that in order to convert an A bromide like the one we have here to a Gilman reagent, you need lithium and copper, right? So what we're doing in the first two steps is we are creating a Gilman reagent or an organo coup is another term for that. And the way that happens is because first of all, our reaction with lithium is going to actually replace the bromine in this case. So when we go ahead and react with lithium, instead of that o bromide, we are going to have an atom of lithium, which I'm going to draw in green. And then from here, right, our organ organo lithium reagent is going to go ahead and react with copper iodine to generate the organo coup that we know as our Gilman re agent, right? So when we react with copper iodide, we actually react two equivalents of our organ or lithium. And so two equivalents of our organo lithium reagent react with copper iodide to generate our Gilman reagent. So essentially, right, you end up with two R groups attached to your copper. So on the bottom, I'm going to draw one atom of copper joining our two groups together and I actually drew it at the wrong position for this one here. So let me just correct myself. There you go. So now the fact that our copper here is bounded to our groups actually gives it a negative charge. So that's going to have a negative charge. And our lithium from earlier is serving as a counter ion with a positive charge. So this is our Gilman reagent and now that we formed our Gilman reagent, we can go ahead and proceed with the later two steps of our reaction beat right? Because steps three and four are now introducing an oxide followed by an acidic work up. So recall, the Gilman reagents can react easily with oxides to produce alcohol alcohols, right? Because we call it similar to a green yard reagent, right. This copper lithium salt disrupts the charge balance in the molecule. Right. Right. And what I mean by that is because my copper atom has the negative charge, it is going to be our nuclear file in this case. So if I go ahead and I draw my oxide, then it's going to be my atom of copper that actually attacks either carbon of my oxide. Right? Because notice how this oxide is actually symmetrical. So you end up with the same product regardless of which one you choose to draw the error on, right. But here the attack of copper on the carbon of the oxide causes the oxide ring to open, right? And one pair of electrons is going to go towards oxygen. So as a result, right, recall that you end up with a tri organo copper intermediate, right? Because not only do you have the two R groups from your original organo crate re agent, you're also going to end up with the R group of your oxide attached, right. And so after reductive elimination, your your copper here is going to dissociate and you're left only with the two R groups joined together. So what that means is that one of these methyl cyclo pentane rings is going to be associated now to the carbon di our oxide. So to show you what I mean by that, right, I'm going to draw our methyl cyclo entine and now we're joining the two carbon diva oxide together, right? So carbon one was attacked by our copper atom and carbon two now has our o minus after the oxide ring opened. So this is where our acidic work up is going to come in in step four of this process, right? So I have an H plus and solution which our O minus is going to go ahead and take and we are left with our final product. Now we are left with an alcohol, we are left with an alcohol and now this reaction is complete, right? So for step a, what we did was we converted our alcohol to an al bromide. And then from there, our alkyl bromide underwent conversion into a Gilman reagent which we then used to react with an oxide and generate an alcohol after acidic work up. So if you stuck around to the end, I appreciate it. Thank you very much for watching. And I hope you found this helpful.

Identify A through O:

Key Concepts

Reactions of Alcohols

Organolithium Reagents

Cyclopropanation and Hydration

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