00:01
Okay, we've got ethyl hexia 2 -4 dienoate and diethyloxylate.
00:34
And we are asked, let's see, in the presence of base, draw a stepwise mechanism for the reaction of ethelhexor 24 dienote with diethylxylate in the presence of base.
00:49
And drawing that mechanism show why it is a new carbon -carbon bond forms on carbon 6.
01:00
And why is this a reaction of an example? why is this an example of a cross -claysant? okay.
01:08
So consider that if we're talking about cross -claysons or that if you have these kinds of molecules in the presence of base, that one of them is going to form an enolate.
01:20
Either directly an enolate or something like an enolate, and it's going to attack the other.
01:26
In this case, only one of the molecules is capable of forming an enolate because this one has no alpha carbons, whereas this one has alpha carbons and therefore has alpha hydrogens.
01:37
But you will note that there's resonance capable of form an enolate, and that this is what they're getting at when they talk about c6, right, because numbering ethyl has.
01:50
Xa 2 -4 dienoate.
01:52
This is carbon 2.
01:54
This is carbon 4 and this is carbon 6.
02:00
And what they're saying is that if we react this with a base, we're not really going to get a useful, right? we can't really make this diene, right? this would be energetically unfavorable, right? so it's unlikely that a base would deprotonate at the alpha carbon on carbon 2, but far more likely that we would see deprotonation instead on carbon 6.
02:52
Base comes in, protonates here, and creates something like an enolate, but a little different.
03:09
I'm going to get rid of this green proton because i think for me, what's useful is if i color code these molecules, right? so i'm going to actually make this enolate type molecule green all over, or at least this part of it.
03:31
And i'm going to make this molecule blue, or at least.
03:42
And perhaps we'll see why in a second.
03:44
Okay, so we form, first part of the mechanism is deprotonation there, forming the following.
03:52
I'll leave myself a little room on the left there.
04:10
And remember still, we've got this over here.
04:29
Basically, what's going to happen is that this negative charge is going to swing down...