If you've got this problem on a test, you can just do that in your head, and now you have your diene Trans about this single bond, so we have to rotate about this single bond here to go from the s-trans confirmation to the s-cis confirmation. But here we have the s-trans confirmation. Up here, we had our diene and what's called the s-cis confirmation. This on the left, this is a diene, but notice that it has an Down here on the left, this is our diene, and on the right is our dienophile. All six pie electrons move at the same time in this one-step reaction. Next, these pi electrons in blue moved into here to form this bond, and then finally the pi electrons in magenta moved into here to form this bond. So, following our electrons, I'll be consistent with theĬolors that we used before, so these pi electrons are red and those electrons move over We know we get a cyclohexene ring here and then we would have our aldehyde coming off of that carbon. If we think about electron density flowing from the diene to the dienophile, I can move these electrons into here so we form a bond between these two carbons, and these electrons move into here to form a bond between these two carbons, and then these electrons down to give us our cyclohexene ring. Let's get some practice with some simple Diels–Alder reactions. What matters is thinkingĪbout moving your six pi electrons to give you

I showed my electrons goingĪround in this direction, but it doesn't matter, you could've drawn your electrons going around in a clockwise fashion. Now I drew my electrons going around in a counterclockwise fashion. To here to form the double bond and to give In magenta right here, on the diene, move down They start on the dienophile and they end up forming this bondīetween those two carbons. Next let's follow these piĮlectrons on the dienophile. If we follow our pi electrons, we'll start with these And that would give us our product on the right over here, which Think about all of those six pi electrons moving at the same time. Two carbons, and then finally, these pi electrons Would move into here to form a bond between these This is a one step reaction that proceeds through a cyclic transition state, and if we think about electron density flowing from the diene to the dienophile, we could start with these piĮlectrons moving into here, so we form a bond between We have four pi electrons, so you can think about the electrons flowing from the diene to the dienophile, and this is what's calledĪ pericyclic reaction.

The diene, on the other hand, is relatively electron rich. We know that phile means love so the dienophile loves the diene, and the dienophile usually has at least one electron withdrawing group, which withdraws electronĭensity from this double bond. On the left we have our diene, so we have two doubleīonds in that molecule. Reaction is a very important reaction because it's used a lot in synthesis to makeĬomplicated molecules.

Maleic acid sigma and pi bonds