 Okay, guys, a lot of you guys have been wanting to do this problem So I guess this problem says essentially what is or how do you get these two different products? These two different dials from this same alkene. So of course, this is a dihydroxylation product our problem exhalation Okay, and you're using this alkene So remember reactions of alkene remember this is a Z alkene why because Z is on the same side, right? So to be a sin hydroxylation so you can have a Sin or an anti hydroxylation remember, right? So to be a sin hydroxylation you're gonna want the OHs to be put on on the same side and to be anti you're going to Have them put on opposite side. So in order to figure out whether this went sin or anti you need to actually have these products and the same kind of confirmation as The starting material to be really obvious So the way I would do it is to take one of the products and just kind of Confirmationally change it so you want to twist we'll say leave this side the same and Twist this side to where we get the methyl in the same spot or the hydrogen in the same spot as on the other side and If well, we can hopefully already see let's just twist this one Down around like that. So if we do that What do we get? We get this side remember stays the same Okay, but this side twist it right so when we did that we were trying to get these Methyl groups and hydrogens or we could think of it as the hydroxyls in the same spot So if the so the hydroxyls are in the same spot So if the methyl and the hydrogen are also in the same spot then we know this is the sin hydroxylation product But if you see if we turn that of course the methyl is still in back there And the hydrogen is now in front So if you see that's opposite of the other side. So this must have been the ante So we can do that same analysis just to make sure So let's hold this side the same and put the hydroxyl groups in the same spot and see what we get with our Hydrogens and our methyl groups. So hold this spot. We'll twist this one Like this and if it's hard for you to do build these and With your model kit and it'll be much more obvious of course, so We're going to Leave this one in the same confirmation this side of the same confirmation But this side twist it this way, right? So we're going to twist the Hydroxyl group from the bottom all the way up to the top when we do that the hydrogen twists to the front actually Here Hydroxyl group is there and of course that must mean that the methyl group is there and you can see this is the sin Dial so we've got the anti-dial here and the sin dial here So Now all you got to do is remember. How do you get? The anti-dial from an alkene and how do you get a sin or anti Dihydroxylation and how do you get the sin of the dihydroxylation from the alkene as well There's a couple of ways you can do it. So that's cool. So if you forget one of the ways then you can remember another one, of course to get the sin dial it's probably more obvious the easiest way is to use the osmium tetroxide and Sodium bisulphite Okay, and that'll go directly to the sin dial Remember the sodium so you make the osmate Intermediate and the sodium bisulphite reduces that Osmated intermediate Or you could use another set of conditions More finicky because you got to keep them at a cold temperature, but the potassium permanganate in a basic solution and a OH At a very cold temperature and that won't allow the oxy oxidation to go all the way to the in this case the aldehydes The two aldehydes it'll stop it at the die the sin dial stage So you can do either one of those and if you're wondering what's the mechanism you can go back to the other videos and look at that So it's either this one or this one. It's not both. Okay, so we put both of course So anti dial, how do you do that? Well, there's the real fast easy way is to first mcpva and that's going to give you of course the Apoxide the three-membered cyclic ether and then when you get that of course you can do Two different reactions to open it. So one of those reactions would be the strong basic conditions so NaOH and water and that's gonna Give you the of course the SN2 attack from the backside of the epoxide opening it from the other way and Giving you the anti dial and there's another way of course and I can see some of you guys are already telling me it's the So This might not be the most obvious way, but you can it's something actually you learned from last semester. So it's BR2 H2o Okay, remember. What does that make? Yeah, that's right the halo hydrant. Okay, so yeah, the halo hydrant is what it's called That thing right yeah the halo hydrant and so that makes the halo hydrant and then what do you got to do? So you're still trying to make the epoxide so it's essentially what you're doing is two steps to make the epoxide for those of you Who couldn't remember mcpda is what this is and then of course then you're going to use a non-nucleophilic base like NaH sodium hydride that'll deprotonate the halo hydrant oxygen and then allow it to do backside attack on the halogen in this case the bromine and And then you can use the same step up here NaOH H2o to open up that epoxide Actually, there's another way that you can open this epoxide So there's another way to do this third step and this is for both of these in this case It would be the second step. So it's either NaOH so basic conditions or acidic conditions H3o plus water That will also so this like sulfuric acid or whatever and that's the same thing here or H3o plus So sulfuric acid and water that will protonate the epoxide of oxygen of course and then Allow water to be the nucleophile and attack. So if you're wondering about any of these mechanisms There's videos of all of them so go back and look at those videos and he should be cool. Okay. Thanks a lot Questions