Show how you would accomplish the following conversions.

Question

b. cis-hex-3-ene to (d,l)-hexane-3,4-diol

Accepted Answer

Hey everyone and welcome back in today's video, we are going to tackle the following problem predict the regions for the following reaction. If we examine the given reaction, we have to understand that we are starting with an L keen. This is this arrangement of that elk in because the two method groups are pointing down with respect to the double bond. So we have sis be it to end. There are four carbon atoms within the parent right? And we're forming a scenic dial. Let's label several important parts of information that we can extract from this reaction. First of all, we are starting with an L. Keen and that Elkin produces a dial. So we may say that the starting material Elkin gives us a dial number two. We understand that the product formed or the dial formed has anti arrangement of the two hydroxyl groups because if you look at it, one of them is pointing up and another one is pointing down. This means that they are on opposite sides of the plane and therefore we call this an anti arrangement considering parts one. And see, we may conclude that this is the answer. Di hydroxy elation of Elkins in particular. One of the most efficient ways to produce an anti di hydroxy elation of al kins is to produce an intermediate where we get an ip oxide first and then we perform a backside attack. So let's use that idea and let's propose possible regions to perform this transformation the world. First thing we want to do, we want to form an ip oxide out of the given al king and to produce in a pox. I'd recall that we may use a proxy asset. One of the common ways is to use EM CPB A. But for the purposes of this problem, we're going to use something simpler. We're going to use per acetic acid, which is CH three C. 03 H. This is per acidic asset. But keep in mind that one of the common regions that we're using here may also be M. C. P. B. A. You will get exactly the same outcome. Now, if we draw our product for this reaction, we understand that we're breaking the pi bond and we are actually forming a carbon oxygen bond within an additional ring here so that be cyclic structure. We may simply withdraw the original skeleton and then we are breaking that pi bond and we're simply adding carbon oxygen bond from here and here. So that's our ip oxide. And for simplicity, we may also label these bonds are as pointing up so that we clearly see what's happening during the mechanism. Later. Now this is our ip oxide. This will be our intermediate and now we really want to protein ate it because the medium is acidic. We have parasitic acid present. We are going to protein ate it. There's a lone pair on oxygen that can easily be protein ated by these acidic protons and then we produce a protein ated intermediate where we still have exactly same structure, but now oxygen will have a formal positive charge because now it's bonded to hydrogen. We need to choose a good nuclear file for us to perform a backside attack and make sure that the arrangement becomes anti. And to do that, we have to realize that because we already have one of the waiters, we need one more and to add that additional hydroxyl group, we are going to use water. Water will act as a nuclear file and recall that water will attack a more substituted position. So because the two positions here and here, they are equally substituted, they have one methyl group. Each water can attack any of them. So it doesn't really matter. Let's suppose that we go with the right one. We have a backside attack which will result in an inversion of configuration and then the loss of the leaving group. So this is a backside attack. And during the backside attack, as we previously mentioned, we will have an inversion of configuration meaning instead of instead of having a wedge here, we will have a dash. Okay, so we are going to redraw that structure and in particular if we do so we get our original form member chain, nothing changes in this position. We are just going to add a wedge with a wage and regarding this one as we already mentioned due to the backside attack, we will have inversion of configuration. So that means we want to add a dash in addition to that. Let's just omit the d protein nation step because we're not worried about the mechanism. So let's just say that we are also deep rotating it simultaneously. And now we're simply adding a wage instead of oh H two. So that's our first structure. And the problem says that it's actually a regime IQ. Right. And that makes perfect sense because if you think about the attack from the other end, what if we chose to attack Depok side from this other end? Essentially if we did that we would get an N. And more of that structure because the inversion of configuration would now take place at position number one. And we may simply state that this product would have a wage right here on a wedge. And then this one. My apologies on a dash. Right? And this one on a wedge and indeed this is a systemic mixture. We have these two as an anti MERS because the configuration at centers two and three has been reversed right from a dash we go to watch and from a watch we go to a dash. So these are indeed in an tumors. And then we may conclude that we have successfully proposed our regions. We may simply state that our our set of regions was number one using parasitic asset. Ch three C. 03 H. So we treated our elkin with parasitic assets to produce an ip oxide and protein ated it. And number two. We used water as our nuclear file to perform the backside attack and produce heiress emmick mixture of two dials and anti arrangement. Right? That that's really important for us. So we may now label this is our final answer number one parasitic asset number two water. Now we may conclude that the correct answer to this question is C. However, if you have any questions, don't hesitate to leave your comment down below in the comment section and thank you for watching.

Show how you would accomplish the following conversions.
b. cis-hex-3-ene to (d,l)-hexane-3,4-diol

Key Concepts

Alkene Reactivity

Stereochemistry

Hydroxylation Reactions

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