25. Condensation Chemistry
Intramolecular Aldol Condensation
Video duration:
3mRelated Videos
Related Practice
Skip to main content
When a diester cyclizes and self condensates, the product is going to be a cyclic beta ketoester. This just makes sense because beta ketoester is always the product of a Claisen. But now it's going to be a ring because it's intramolecular. Chemists just had to make this overly complicated and apparently the guy that discovered this specific cyclization was called Deichmann. This is also called a condensation. But don't get too hung up on the name because really all it is is an intramolecular Claisen. Intramolecular Claisen and Dyckman are the same thing. Once again, we're going to determine where to form enolates based on or if we should, based on if we can make a 5 or 6 membered ring. Esters are a little bit more simple because I don't have possibilities on both sides. I only have really 1. Would that enolate make sense? Would that give me a 5 or 6 membered ring if it attacked the other ester like this? Let's see. That's perfect. 6 membered ring, we know that that's going to be favored. What I'm going to do is draw the rest of the mechanism which would be O facing up. Once again, since I have a 6 membered ring, I'm going to draw my six numbers. I'm going to start at this corner and I'm going to move my way around counterclockwise. Really you can start wherever you want but this is just the way that I like to do it. Now I'm wondering what's missing in the different places. Let's even just do the whole mechanism. At this point of the mechanism, what's missing? It looks like 1 is missing an ester. Let's add that. 1 is missing this whole ester thing. What else? 6 is missing 2 things. 6 is missing an O negative and it's missing an O18. Perfect. Now that looks like it's correctly drawn. I'm going to erase the numbers because we know we did it right. Do you know what the next step of this mechanism is? What's the next step? The next step is that I have to kick out the leaving group. I would reform the ketone and kick out the O E T. What that's going to give me is a compound that now looks like this. O E T and then ketone. Now what I'm wondering is guys, did I get the right compound? Because remember that whenever you get a dicmon, a dicmon should always yield a cyclic beta ketoester. Is this a cyclic compound? Yes. Is it a beta ketoester? Well, I still have an ester and I have a ketone of the beta. So yes, this is correct. Cool, right? So intramolecular. Got to get used to it in this chapter. This isn't the last time it's going to come up. It's going come up again. I'm warning you. Get good at it now. Let's move on to the next topic.
05:52
