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Current time:0:00Total duration:3:57

Video transcript

for this diels-alder reaction i've added on an electron donating group to the dyeing so here's the dyeing and notice there's a methoxy group attached to this carbon that means there are two possible regio chemical outcomes for this diels-alder reaction so we could form this product or we could form this product so which product is favored to figure that out we need to draw resonance structures for both the dying and the dyno file and let's start with the dyeing we could take this lone pair of electrons on this oxygen and move them into here and then push these electrons off onto this carbon so let's draw that resonance structure so now this oxygen would have a double bond to this carbon and then this carbon would have a lone pair of electrons on it let me go ahead and finish drawing in the rest of these bonds and this oxygen still has one lone pair of electrons on it which gives us oxygen a plus one formal charge and this carbon would get a negative 1 formal charge let me highlight that carbon so this carbon right here gets a negative 1 formal charge let me draw in my resonance brackets here let's look at the Dino file next so we know that this oxygen is electronegative so electron density is going to flow towards that oxygen I can take these electrons and move them into here and these electrons come off on to the oxygen so let's draw that resonance structure we would have a double bond here and our oxygen would have three lone pairs of electrons around it which gives that oxygen a negative 1 formal charge let me put in my resonance brackets and notice we took a bond away from this carbon so this carbon down here gets a plus 1 formal charge so our dine has a carbon that is electron rich and our Dino file has a carbon that is electron poor and we know that opposite charges attract so we could just line up these two carbons and that allows us to predict the regiochemistry for this reaction technically the diels-alder reaction is not an ionic reaction it's a pericyclic reaction but this trick does allow you to predict the product so let's go ahead and use it let's get some more space down here and let's redraw our Dyna file first so let me draw this in so we had our double bond and then we had our carbonyl we know that this carbon down here is the one that is electron-poor so I'm saying that's partially positive so we need to line up that electron poor carbon with the electron rich carbon on the dyeing so we want to make we want to make this carbon the electron rich one and that means the methoxy group must come off of this carbon and now we can see the regiochemistry for our diels-alder reaction remember the diels-alder reaction is a concerted movement of six pi electrons so these pi electrons going to move into here to form a bond between these two carbons these pi electrons move into here to form a bond and these pi electrons move down so we form our our cyclohexane ring and then we would have our methoxy group coming off of this carbon and we would have our ketone coming off of this carbon so following our electrons so these electrons in red formed this bond and then our electrons in blue formed this bond and our electrons in magenta formed this bond so this turns out to be the product of our diels-alder reaction and let me go back up to here so that's our product as opposed to this one