This presentation will cover the dial's alder reaction by looking at the mechanism and the effects of the stereospicity in the dienophile. Let's start by discussing the mechanism. There's four main components that we all need to remember when talking about the mechanism of the dial's alder reaction. Three pi bonds are broken in order to form two new sigma bonds which are located there and there and a new pi bond. This reaction is always initiated by heat. The product is always going to be a six-membered ring and this reaction is always concerted. So just to show you where all of these broken bonds end up going, the electron pair will push off one of the double bonds in the diene, attacking the alkene of the dienophile, which will push this electron pair off to attack the other double bond of the diene. And then this electron pair will push off to form the new pi bond. And we did color code the diene and dienophile double bonds so that you could follow which pi bonds were broken in order to form which of the new bonds. Okay, so now let's take a look at how to draw the mechanism and product of a dial's alder reaction. Our first step is going to be to rotate our diene about its sigma bond in order to make sure that it is in the SC's confirmation. Step two will be to place our diene a file with its double bond as close as possible to the diene. Next we're going to draw arrows to show what bonds are being broken and what new bonds are being formed. Being very careful exactly where we point them. And then finally we are going to draw our product which just has all of our new bonds drawn in. And the one thing we want to be careful about is what a BIA is about to discuss further with you which is that the stereochemistry of the diene a file is retained in the final product. Now we'll look at stereospecificity in a deal of alder reaction. So in our first example here we have a reaction with a cis diene a file. This means that the substituent groups in the diene a file are on the same side. Because they're on the same side in the reactants, they end up on the same side in the products. And because you could have either this product or this product, both of these products are the same and are called Mizo or identical products. On the other hand, when you have a trans diene a file, this means that the substituent groups are on opposing sides and you get two anantiumers with trans groups on opposing sides. So one basic rule to follow with stereospecificity is that the stereochemistry of the diene a file is retained in the product. This means that a cis diene a file yields a single a chiral Mizo or identical compound. And a trans diene a file yields two anantiumers with trans groups. Now we're going to talk about the retro synthetic analysis of diesiled reactions. And one of these is just the reverse the dies reaction. So in this case we start with the products and then we end with the diene and diene a file. And I just wanted to point out that the two lines with the arrow means that the reaction is going to reverse. Now I'm going to explain some of the rules or tips for solving these problems. The first thing we need to do is find the 6-member ring with alkene. So here is the 6-member ring with the alkene. And then we have to draw in the three arrows to reverse the reaction. So when we are forming dies reactions we are breaking three pi bonds and then forming one pi bond and two same bonds. However when we reverse the reaction that means we need to break one pi bond and two same bonds and then reform three pi bonds. So in this reaction we are showing the arrows. We're breaking one pi bond here, one single bond here, one single bond here. And then we are reforming the diene and diene. So here is one pi bond, one pi bond, one pi bond. So these are the three pi bonds we just reformed. And it's always important to reverse the arrow commit through when doing these reactions and I will explain more in the next slide. Now I'm going to show you some examples of how to do these reactions. So in the first example here we have the 6-member ring with the alkene and then we need to draw in the arrows. So we have one pi bond breaking, one single bond breaking, one single bond breaking and then we have one pi bond forming, one pi bond forming, one pi bond forming. And then in this case it's a little bit different because now we are showing the stereochemistry. So these two are on the same side and in the end you have to have the product recipe on the same side. And then the next one is kind of the same thing. You are doing the same arrows and then we have the same product. And the reason why we have the same product is because there is symmetry between these 6-member rings. Now the last example we have the stereochemistry is just a little bit different because we have the two going in opposite directions. So in the end your product needs to have the lines going in opposite ways.