Develop syntheses for the following compounds.
As starting mater...

Question

Develop syntheses for the following compounds. 
As starting materials, you may use cyclopentanol, alcohols 
containing no more than four carbon atoms, 
and any common reagents and solvents.
(a) trans-cyclopentane-1,2-diol

Accepted Answer

Hey everyone and welcome back into this video. We are going to devise an approach for the synthesis of sis wan come to psycho heche saying die oh you can start with psycho hexen on any region that contains four carbon atoms or less and any required region or solvent. As the problem suggests we may start with psycho Jackson on. So we are going to draw our six member ring that psycho hexen on. And according to the context of the problem we wish to form since one comma two cycle hexen dial. So that will be our sixth member growing. This is a dial. So that means there are two adjacent alcohol groups because the positions of them are one comma two. And to the fact that it says we're going to draw both of them pointing up or based on the same side of the ring. If you draw to register two dashes, it doesn't really matter because if you notice this is a measles compound, it has an internal line of symmetry. So this is says one comma two cyclo hexane dial. We want to think how to get from that key tone to dial and we will actually think in reverse because it'll be easier for us. Okay, so how do we get dials in general? One comma two substituted dials. We essentially have to use Elkins. This is one of the major reactions that we know recall that whenever you use an L king, you can essentially perform an ip oxidation and then followed by acidic Hi trolley sis to open the ring in this case because we're forming a dial insists arrangement. Writer two alcohol groups are on the same side. We want to use either osmium tetroxide or for example, but as soon permanganate in the presence of basic conditions. So if we use this set of regions, we are going to form a dial out of an alky and immediately insist arrangement. The reaction is theory of specific. So it's really important to use appropriate regions here. So either potassium permanganate in the presence of a base or we can also use osmium tetroxide that's perfectly fine as well. Now, how do we get an elk in and notice that we're trying to get to our starting material. We can get our we can get Elkins generally by acid catalyzed dehydration. And that makes sense because if we get an alcohol out of a key zone that would work for us. So we go one step backwards, we can say that we want to somehow get that elkin and to get it to get at alki. And we can essentially start by drawing an alcohol thinking about the fact that generally we can get Calkins by asset capitalized dehydration. So why don't we draw an alcohol? Because look, if we use sulfuric acid in the presence of heat, we call that this is an E one mechanism right? We are going to protein, eight hour O H. It will be a good leaving group forming a carbo Caroline and then upon the removal of the beta hygiene, we are going to get our elkin. So that works for us. And now we have a direct connection between these two. We can say that we now want to get our ketone. How do we go from ketone to an alcohol essentially. We're reducing our ketone right? We can use a mild reducing agent which is sodium borrow hydrate. However we can use lithium aluminum hydrate as well but it's a strong reducing agent. Why do we use a strong reducing agent when we can use a weaker one which still does the same job. Right? We can use sodium World hydrate and stuff. So this works for us. Now let's review all of the stuff. So number one we start with psycho hex alone and we're saying okay we're going to reduce it using sodium world hydrate. If we reduce that, we get our secondary alcohol. When we get our secondary alcohol we're saying okay we want to produce an alkaline and the way to do that is to use an acid catalyzed dehydration. So we're using sulfuric acid in the presence of heat reaction Number three when we got our alki and we understand that this reaction is stereo specific. So the dial that we're forming must be sis and we said one of the ways to do that is he's but as in permanganate in the presence of base. Once again, don't forget there's another possibility to do that. If your choice is to use osmium tetroxide, that's perfectly fine. Now, we may simply say that these are our final conditions. We may just label our final set up for agents, and we can conclude that the correct answer to this multiple choice question is a however, if you have any questions, don't hesitate. So leave your comment down below. Thank you for watching.

Develop syntheses for the following compounds. As starting materials, you may use cyclopentanol, alcohols containing no more than four carbon atoms, and any common reagents and solvents. (a) trans-cyclopentane-1,2-diol

Key Concepts

Synthesis of Alcohols

Stereochemistry

Reagents and Solvents in Organic Synthesis

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