Show how Diels–Alder reactions might be used to synthesize the...

Question

Show how Diels–Alder reactions might be used to synthesize the following compounds.

(i)

Accepted Answer

All right. Hello everyone. So this question is asking us to provide that deals all the reaction that produces the compound given below. So as mentioned before, the reaction in question is deals older and deals older if you recall can otherwise be referred to as a four and two cyclo addition. And it's a four and two cycle edition between a conjugated dyne and a Dienno file. In this context. A Diop is an all keen or an all kind with high equivalent or sorry, high affinity for the di hence the name. So essentially four atoms. In this case, four carbons from the conjugated dyane combine with two from the Dienno to produce a six membered ring. This is characteristic of a deal's older reaction. And what's also characteristic of deals older is that that six membered ring will have a double bond inside of it. So our task right now just looking at the structure of the target product is to identify that six membered ring. Once you've identified the six membered ring, you should also go ahead and identify the double bond that's inside of that deals all the ring. This is because that double bond is going to be very important in helping you understand where the dying and Diop file combine. So basically the bond of the ring that is opposite to the double bond is going to be from the Diano file itself. So once again, the two carbons that are opposite to the double bond of the deal's alder ring or the carbons from the Diop from the alkin or all that participated in the deals, all the reaction. So once we've identified those carbons, our task now is to separate them from the remaining four of the deal's alder ring. That's how we get our dying and dying of file. But it's not as simple as just separating these carbons from each other. Because during the Deal's older reaction itself, we have three pi bonds in total. We have two from the dying and at least one from the Dyal file, two of these pi bonds become sigma bonds to allow for the formation of the ring. So in a question like this, where we're going backwards in a retro synthesis question like this one, make sure to add those P bonds to the structure of your reactants. So let's start with the dying on the left side of the split that I drew, separating the dyane from the dino file. Now, these two atoms here that are bridged on top of the Deal's older ring are going to be part of the dying itself, which means that the dying was itself a ring, specifically a six membered ring because we have more carbons from the dying itself. And the two carbons or excuse me, two atoms from the bridge, one of them is carbon and the other one is sulfur and that sulfur has two double bonds, two oxygen atoms. All right. So here in terms of adding our double bonds, recall that the dying in dios alder is conjugated, which means that the two pi bonds should be separated by one single bond in between. So that takes care of our dying. Let's talk about our dienno. So after identifying the two carbons that came from the Diop, it's important to check for any substituents. This is true for all carbons. But here in the carbons from the Diop specifically, we have two nitro groups, one on each car. What's interesting is that both of these carbons or rather both of these nitro groups are pointing in a different direction. What that means is that they are trans to each other. Now, one thing about the deals, all the reaction is that one relevant, right. Substituent. Did I spell that? Right? Yes, I did. OK. As I was saying, one relevant substituent stereo chemistry is retained after deals order. And so if in the structure of the target product, these two nitro groups are trans to each other, that means they were also trans in the structure of the starting material. And so now that we've talked a little bit about stereo chemistry recall that py bonds must be added. In this particular case, the two carbons from the Diop in the structure of the target product have only a single bond in between them. That means the Diop was an all keen. Now, by contrast, if there's a double bond between these two carbons in the product, then the Diop was an all kind. But here it's an all king and it's an all keen with each carbon having a nitro substituent. Furthermore, these nitro substituents are trans to each other on opposite sides of the double wand and there you have it here is, or here are the two reagents necessary to produce the product given. Now, it's also worth mentioning that heat is added to deals alder to carry the process forward. But with that being said, thank you so very much for watching and I hope you found this helpful.

Show how Diels–Alder reactions might be used to synthesize the following compounds.
(i)

Key Concepts

Diels–Alder Reaction

Conjugated Dienes

Stereochemistry in Diels–Alder Reactions

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