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Lecture 04. Reactions and Protecting Groups.

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the regular Europe enters down ground but what I did so
much so much of what
happens in learning organic chemistry is not about the the
need for about Johnny or about him it's about you know and actually working properly and you're one-sixth of the way there with the quiz is and you're good fracture fractured the way there with their homework here on board and you're keeping up now this place may have been a overly easy champion Chapter 19 wasn't that we like this gives you the flavor the next 1 of probably ask you some questions about mechanism about synthesis and Kerberos for bigger things that development around the good set of scales fight the quizzes are going to build on this problem solving aspect of the course and the skills that you cultivated and the work that you put in preparing for this and doing the homework is existed exactly what's going to set you up to excel in the class so again it round about what readers so today today I want a move into the last section of Chapter 20 Chapter 20 is kind of interesting because it has that kind of different stuff and it sort of is all over the map in terms of reactions and I thought about it and what I've tried to do is really the group things being the conceptual themes and the last conceptual themes that I see from this introduction to Chapter 20 and as I said this is only a part of Carbondale chemistry because we're going to be continuing through 4 chapters well 5 chapters 6 chapters technically 19 to I think 24 on carbon chemistry it's a huge swath of the course 7 weeks so in breaking out the last part of Chapter 20 what I'd like to do today is to talk about selective reactions of carbon your groups in the car the old family and also about the use of protecting groups in synthesis so I'm going to start with the sort of a conundrum I raised and in yesterday's class and that is that we talked about the addition of various types of nuclear files to Astor's we talked about edition of powerful hydride nuclear files like lithium aluminum hydride and powerful carbon-based nuclear files like organic lithium reagents going yards regions and we said in those reactions you would typically take the Ester Remember the asterisk plus 3 oxidation state of carbon and not move 1 step down 1 notch 1 pair of steps down but moved 2 steps down to the primary alcohols oxidation state in other words if we'd taken master like methyl benzoate weight is the 1 I wrote in the previous class and we treated with lithium aluminum hydride and then we carry out make this work out with water history textbook rides to 3 of plastic reassesses might beat Seattle in water the product of the reaction is Denzel alcohol but organic chemists are often really bad about writing small molecules and by-products of reactions are just remind us of course the other product of this reaction is methanol and fire affecting about a synthesis maybe I wouldn't want to write it but if we go ahead and do the same chemistry the same substrate methyl benzoate away and now instead of treating it with lithium aluminum hydride we treated it with save methyl lithium for methyl magnesium bromide but In all specified that we're talking about 2 equivalents here although we really can't get away from problems happening from from the lack of stopping happening and then again we do some type of 8 weeks work out now we've gone down and added to equivalents of the methyl group has gotten this tertiary alcohol and the main point of this example is that we cannot stop these reactions he had lower they go through the intermediate of Ben Zelda hired for the former and for Benesova known on the latter part 1st known on the latter we can't stop the first one had been Zaldivar highlighted war the 2nd 1 head a Seidel Final so organic chemists are all about control were all about being able to
choose and to develop tools to make the chemical compounds that we want to make and we have a conundrum here in the lack of select activity the lack of ability to select for the AL behind were the key to this are question over there from the gentleman in 3rd but for an exam or we going to have to put the by-products question very reasonable questions when I'm thinking about a synthesis and I'm thinking about taking my than methyl benzoate on through several steps to a product that contains that benzene in the carbon in the Mathilde just some sort of a throwaway Ibirite wouldn't write but if I'm thinking about writing and in equation or balanced equation which I shall Wall products of reaction or mechanism I certainly was question I know and I know these little variations end up being of tremendous concern due to you wonder why sometimes called pairs wide away
sometimes brought Kerberos to show mechanisms and Helen thinking and other times we just steps from reactants for product it's expressing different things 1 is expressing a level of detail how how the reactions occurring and the other is what were forming on the were remitting the methanol simply what were will forming part as the fact and here I guess I will fight to keep consistent in the 1st panel here I will begin to sort of parenthetically right methanol is the product but the question and then a very very legitimate concerns particularly when you're starting out learning and trying to to figure out what people were expecting new you are sold Tennessee 7 developed a number of different reagents to achieve selectivity in these types of reaction is another question Top another good question so your text sometimes shows things as covalent bonds and sometimes as ionic bonds we're going to see that today to some extent in general lithium and magnesium when bonded to carbon are primarily covalent and their bonding sodium is a little more electoral positive it's more ionic in its bonding sometimes will write an ionic
residents structure mentioned in the last lecture will sometimes in our mind think of methyl lithium as methyl minus With a lone pair lithium plus that's a nonviolent residents structure but the main resonance structure is the covalent 1 alright so on the selectivity and
control so your textbook represents 1 reagent to do this reaction selectively that reagent is delighted now diaries and aluminum hydride since 1st let me write this as a as a synthetic reaction and so if you take the reagent died this reagent has 3 different different names that that people following depending on the source you go to work the reagent is dying I said aluminum hydride it's too I said will groups and aluminum on hydride and and a hydride on hydrogen on aluminum and you will see it written sometimes as died down with an age on the end to indicate there's a hydride sometimes as died down without the DH on the end and sometimes as a guide fast just because people I want catch the notion of the age anyway if you train your Astor with died out and then a work up and again you could add water for I would probably had a reassesses the product of reaction is the AL you can stuff the reaction at the elder highly the byproduct of the reaction would be the methanol as a byproduct so then just here it is just as we've dealt with other sorts of nuclear files like methyl lithium adding to a Carbondale here we have a hydrogen nucleophile hydride nucleophile on aluminum and the overall result the part way through you get attacked over here all intermediate so so you're metal bends away reacts with Dyson Beutel aluminum hydride to form detector he will intermediate with your aluminum and your too I said bugles on there but the main thing is because the aluminum oxygen bond is very strong stronger and more covalent again is this notion of degree of covalent C free of ionic nest because aluminum is a little bit less Elektra positive than say lithium you have more covalent bond character you form a very strong bond to oxygen and you have attacked he'd intermediate but that's stable enough to not break down all right it is more stable debt-free legal intermediate in another words your Tadahiro intermediate is sufficiently stable that until you carry out the 8 Rios work up until you add Water are you add but we assess if it sticks around the remember the mechanism for this double reaction when lithium aluminum hydride hydride ads you get attacked intermediate detector intermediate breaks down kicking out a meth oxide leaving group that gives you the elder hide another mole of hydride adds giving you a new text retrieval species your
final Alcock side that permeates and worker and so at this point you can stop the reaction now in practice is sometimes
a chemist would choose to use died as a reducing agent to stop at the Al the hide and sometimes it can afford say alright look I'll
just use lithium aluminum hydride reduced all the wearer down to the Alps to the primary alcohol and then reduction then oxidized Denzel alcohol back up to the all the
sometimes in practice it's a little more efficient 1 way or another as in many cases there are at multiple ways to multiple right ways of doing things and in the laboratory canvases often concerned about what's easiest for what's what gives the best overall
chemical view the vast amount of product in the end alright so that
takes care of achieving selectivity In our reaction to add a hydride nucleophile let's now take a look at achieving selective in anonymity the alkyl nucleophile known as late as I said before carboxyl like acids are part of a big family a family in which your carbon is in the Plus
3 oxidation state in all of these species are easily injured converted you'll be learning more about these in conversion reactions in the subsequent chapters carboxyl like acid
esters acid chlorides asset and hide rides part and it and even nite tree also end up being all in this plus 3 oxidation state family of carbon so in order to achieve selective edition of an analytical group we're going to use a different Member of the carboxyl against family in acid chloride and you'll learn about how to 4 massive chlorides later on now if you just treated almost almost any member of the carboxyl like acid family with inorganic metallic roots and organic metallic cool iPhone with where the Gargano metallic nucleophile so we treated it with the same at the lithium or metal magnesium worldwide we would have and again I'll indicate that we're talking about 2 equivalents but the main point is that we can
really stop and 1 equivalent if we in other words if you added 1 equivalent it wouldn't stop at the key tone in the other case we just get a mixture of the alcohol and on reacted Esther in some detail on it wouldn't be a controlled reaction so imagine trading with
Mathilde lithium and then in the 2nd step again Mary quiz were Campanile just right this is revealed lost his mind where we certainly throw reassesses the year the problem as we begin the exact same situation that we were with methyl vans away we would have to equivalents of Mathilde Mathilde nucleophile
adding here we really don't have control and this is essentially the same thing in their little variations your text but this is kind of the same thing with lithium aluminum hydride if we treated lithium aluminum hydride with an acid chloride or carboxyl Aghazadeh Estherwood always reduce it down there little variations in reaction of green yards organic lithium's with carboxyl like acid terrible variations which text that gives you an example on and the reaction of lithium aluminum hydride with our minds to give you 1 means but for the overall general principle it's members of carboxyl family with this powerful new these powerful nuclear files lithium aluminum hydride green yard reagents and O'Donnell
lithium compounds all get edition of 2 equivalents and all stick out the leaving the question no and you can easily write access in my own laboratory people would probably use two-and-a-half or 3 equivalents in order to be just to make sure that there was enough of the reagent to achieve the reaction by the out would be a minimum of 2 equivalent but as I said a few years less you wouldn't still wouldn't be able to to stop and control of have the tone from alright they reagents that people have developed to make this reaction selected because what this is all about is selective idiot achieving the reaction that you want to work on the reagent that people have developed to make this selective is organic who prayed reagents all right the reagent 1st and then I'll show you how you make it so the reagent here is dying methyl is lithium dynamical who prayed CH 3 2 C U L I it's a carbon nucleophile again now we have carbon bound to copper copper is even less Elektra positive then lithium lower aluminum and so it's even more of a covalent bonds the exact mechanism of the reaction goes beyond the scope of this class but in the very last lecture if we go on schedule and talk about 26 Chapter 26 of giving
you a little bit of a flavor of the various special reactivity of transition metals like copper and palladium but that will be later on if we have
time anyway the overall result of this reaction is that you can control Mobley had won the equivalent all of your methyl groups To hear a member of the carboxyl like family in this case specifically here acid chloride for reasons of than activism and organic fruit great reagents can be made by the reaction of 2 equivalents of methyl lithium with comparable iodide to give you CH 3 2 see you L line which as I said it's called lithium die methyl group break of the annual also you wanna ride a balanced equation which as I said organic chemist Clinton the very bad at your death lithium iodide as the other
by-products Of the reaction there are many subtleties in this chemistry many of which go beyond the scope of the costs certain groups like Apple groups to what's called beta hydride elimination don't work as well in this reaction textbook gives you examples of final troop break those work well certain crew parades like acetylene son copper don't transfer at this point I'm just giving you in your textbook is just giving you a teeny taste of this being Wide World of
selective reactions fear another way 1 can actually achieve this reaction selectively is to add a little bit of copper children yard reagent but again we're not going to focus heavily on any of that right now I just want to give you a little flavor as you text textbook does all this notion of control in reaction question for the for the exam is a very good idea to know pushing for for organic lithium reagents in Bromyard reagents and lithium aluminum hydride and overall principle of reaction of the carboxyl like acid family the addition elimination reaction of the 1st nucleophile followed by the addition of the 2nd nucleophile but for more specialized free agents like you're down to break agents as I said the mechanism goes a little beyond the scope of the for
alright so this brings us to 1 notion here of control and specifically
the notion of the most selective that is achieving control
for the reaction of 1 group but not another in a way that we've already seen that notion in these 2 reactions and that were controlling the reaction to get just to the Alger highlighted Hideaki the tone oxidation state but really the best sort
the archetypal examples of chemo selective when you have 2 functional groups and you wanna carry out a reaction on 1 of those functional groups to the exclusion of the the other functional group so let us take and again like many of my examples in the class they'll be a little bit artificial in the sense that you might not immediately have a reason to do this let's take a derivative of a compound called terephthalic acid where we have half of it
as the AL Haydn half of it as the Esther and reimagined treating this buying carbon Neil compound this dike carbonyl
compounds with lithium aluminum hydride and then with a Prius acid lithium aluminum hydride is last down all of the members of the carboxyl extensive family of produces all of them it's a super powerful source of hydride nucleophile and so our Esther group gets reduced not just write it as waged to tell us that we have the alcohol but In our held high gets reduced to the alcohol in other words this reaction is not she most selective it doesn't hit just 1 group now conversely if we take a milder reducing agent like sodium hydride then we do get selective adding soldiers right did 0 mark through for the reactor here and then alright sodium or hydride typically people use alcohol solvents like methanol Brazilian-born hydride reduction if we carry out the reaction of as Durao the highs in with sodium or hydride then we will selectively reduce the elder high group with help reducing the Astor Place but if we say that sodium or hydride is chemo selective the different beers is the hides and I might add tones but not esters but but but but but but but but but but but but but but but but but but but but but but but it of of and so that principle of control is something that's very useful because it allows you to make a product that
you desire and as I said so much of organic chemistry is about making molecules that often are useful for for example drugs however I want to give you a couple of other examples of selective Betty and I borrow these directly from your text but there are many ways to do these types of reactions and I thought this example which is straight from your text would
actually illustrates the point where it is so if we take a compound like cycle taxi known which has both a carbon-oxygen double bond the carbon Hill group and the carbon-carbon double bonds we have 2 2 different groups that can be reduced the carbon-oxygen double bond and the carbon-carbon each of reagents like sodium were hydride the lithium aluminum hydride an American right all the conditions are just right sodium embarked hydride lithium aluminum hydride reduction and reduce the carbon Neil group these reagents are nucleophilic toward carbon meals they add to the carbon your group if we take this same cycle taxi known and instead performed catalytic hydrogenation on your textbook writes 1 equivalent of hydrogen and I will add more low pressure in other words the way you could do this reaction is eager to go ahead and control the amount of hydrogen that you're adding war carry out the hydrogenation quickly at with just a
balloon of hydrogen at atmospheric pressure monitoring by TLC and you do this in the presence of a palladium on carbon catalyst or
platinum catalysts the textbook uses palladium on unguarded as an example you can selectively reduce the carbon-carbon double bonds since so go from cyclo hexagon only To cycle texts
are known hydrogenation of carbon meals are more difficult it requires more effort to reduce the carbon oxygen bond in other words hydrogenation is chemo selective for the carbon-carbon double bonds but if you beat
on your textbook writes it as age 2 excess that might be a big balloon of hydrogen and monitoring the reaction for a long time were sometimes people will carry out these reactions at higher pressure also a high pressure by high pressure it can mean anything from bicycle tell us
attire to which pressure of white 75 PSI in a special glass bottles to an apparatus that steel with a tank that can hold thousands of PSI aptly called bomb if 1 hydrogenated under
high pressure extending the catalyst that can be polite human cognitive platinum oxide or any of that platinum family of metal then you can reduce both the carbon-carbon double bonds and the carbon-oxygen violence and again when his achieving control 1 is achieving
chemo so activity in this type of reaction the entire books on the topic of catalytic hydrogenation effective book by that title so there's a lot
of different ways to do this reaction and again your textbook is just giving you a little taste which is fine because it gives you a lot of the needed thought processes no In these reactions on this flight poured we've looked at taking the oxidation stayed down in 1st case we took the oxidation state of the carbon-oxygen double bond down we reduce the oxidation state of the carbon in the 2nd reaction we've reduce the oxidation state of these 2 provinces and in the 3rd reaction we've reduced
involved just as there are many ways to reduce the oxidation state of carbon there are many ways to increase the oxidation state of carbon to oxidize pardons and your text that gives you a little taste they give you 3 related sets of oxidation
conditions the oxidizing primary alcohol up to a carboxyl aghast at all the ones that they use that they show you involved chromium it's a classic potassium call made or sodium potassium dichromate or sodium dichromate for chromium trioxide in sulfuric acid and water are all essentially equivalent to all of these are oxidized primary alcohols up to carboxyl likenesses there are new or more modern reagents that don't
use toxic and carcinogenic chromium textbook leaves those out that's fine as a said you can write an entire book that although there are
ways to stop at the elder hideout oxidation state and your textbook gives you 1 such said of reagents the use of silver oxide in the various ammonia and that most of you at the other side of oxidation state again what this is all about is about control In chemo so activity all right so I guess my conclusion I will just right there are many other selective oxidizing agents but which are right at this
point I would like to Churdan turn my attention to another problem so we look at the problem of chemo selectivity and at this point I'd like to turn my attention to the problem of Regio select in we've kind of seeing this issue already With the hydrogenation question and I'd like to give us the same same type of example and we bring back on Cooper and reagents so here's a cyclone hacks and our taxi known again and if we treat our cycle 16 with a powerful nucleophile we already saw lithium aluminum hydride and how they'll give you an example of methyl lithium green yard reagents cultures methyl magnesium bromide just as an example and then we carry out innately Rios worked we had just like the lithium aluminum hydride did we add to the current annual group the powerful nucleophile attacks the carbon Eurogroup what's interesting with this alpha-beta unsaturated carbon compound is if we treated with an organic great reagents all just right it did all mark and then I'll bring back our lithium died methyl group great and again will carry out some type of a Rios typically reduce acid now we get of various different sort of edition the addition is not to the carbon-oxygen bond but rather to the carbon carbon bonds in what we call a 1 4 additional inability to contrast that to the previous example which we call a 1 2 edition In I'd like us to think as I said we're not going to really
fast about the mechanism of the freight reaction in detail and it cut or to put it more specifically wide copper does what it does the reasons for the details of the differences around the start subtle but we're going to flock focuses on the nose and the what's the house and the what's that are happening so in 1 2 0 edition appears on carbon yield on 10
years around forbade unsaturated carbonyl compounds accorded alpha-beta unsaturated Cardinal compound because the carbon that's next to the carbon your group we call the Alpha carbon and the carbon that's 1 over we called the beta copies so in the 1st example Our nucleophile which we could think of is Mathilde minus sir we could think of it as as a baffled bound to Alethea but I'll just write it is in new minus nucleophile attacks the carbon Neil group and I'm going to dry in the current lone pairs of electrons to help us think about this and all drawn occurred world the nuclear from the thing with the electrons to the Electra filed to the thing that once the electrons and I will punish electrons on so the carbonyl oxygen because of course if I stop at this point I would have 10 electrons around the carbon and we would be in trouble so at this point in the mechanism we have warned Cox side and on the nuclear file has added not how your 1st reaction to this and 1 of the things that was guiding our thinking and thinking about the reactivity of the carbon EO Group is we recognize that although the carbon-oxygen bond is a covalent bonds it is the polar covalent England we embodied that last time were the other time when we talk about this we embody this in 2 ways 1 was riding a Delta minus on the oxygen in the dealt the positive on the part and the other way of embodying you're thinking about this case to write to different residents structures and so I can write 1 resident structure like Whitesell the main resonant structural nature residents structure and then I can write a 2nd resonance structure that reflects the polarization of the bond with the carbon doesn't have complete
architect and it's not as important to residents structure because a resonance structure in which the carbon doesn't have a complete architect is less of a contributor but I can also write a
3rd resonance structure and the 3rd president structure is to continue to move the electrons of the double bond much as you do it in a little like Cat Island which you learned about in the previous quarter and now you have your positive charge over the bait of possession and in order to help avoid confusion that I want to in Meiji hydrogen is here so that you can see that just like the resonance structure at at which you have the positive charge and the carbon carbon this last resonant structure this other minor resonance structure has a positive charge on the beta problem which has 1 of the hydrogen in other words it doesn't have a complete I had either so collectively these 3 residents structures make up a more complete picture that help us think about the the reactivity and in the case of the 1 for additional again we're going to skip the lines of it at this point in Europe learning of organic chemistry but in order to understand the reactivity I'm the 1 for addition reaction you can say
OK now I can see why in some cases by nucleophile is going to react at the carbon your carbon and at other cases because
there is also a partial positive charge into major positions at some cases the nucleophile is gonna add to the beta Caribbean and now we just assure electrons like Sony apart from the represent the think about the reactivity here but on now that kind of talk us halfway through the conjugated addition through the 1 for edition of the compressed because we did a 2nd step where we did an increase worker and the product that reaction which had just racist abuse on the bottom of your right hand like Ford was Quito and at this point we're halfway through we don't have a key tone and were about to add a source of Aquarius Anderson now the species that we've just generated here is called an e-mail late and I have and this is your 1st exposure to the delayed and undergoing to be learning more about it in a moment far more specifically you're going to be learning more about you later on islands in Chapter 23 so here it is the EU late and and just like the European you can think about it having multiple residents structures again this is going to come back more later on so we can think about 1 structure indeed it's going to be a major resonance structure the major resonance structure which I've written on the left In a 2nd resonance structure which I've written on the right and you're going to as I said at the scene were about these in Chapter 3 but for now what you can think about is that in the work up steps of the organic Cooper reagent you probe may be in a light and you can think of it is occurring in 2 different ways I'd probably like to think of it more in the way that I'm riding over here you can think about the the proton going onto the Alpha carbon to give rise to your heating product in terms of authentic racer in terms of the greatest simplicity that's probably the way I like to think about it your textbook writes the mechanism slightly differently and that's OK too your text that likes to think about the proton going on said the oxygen white snow and this product is called an e-mail and he and all is in equilibrium or ghost of former the key town by a reaction which again you will be learning more about and Chapter 23 called Todd summarization of the right that again we called it the tone and the in all forms what emerged then we call their conversion taught summarization
and the current this this issue
of selectivity and achieving control is 1 that cannot always be done by picking the right reagent in other words sometimes you could say Oh yeah I wanna green yard reagent here I want Kubrick reagent here I want lithium aluminum hydride here I want died valve there but there are cases where 1 gets into a situation where no amount of choice of the right reagent alone is going to do something allow you to do something that you want to do and let me show you an example of this and can work around the mansion that I wanted to generate a green yard reagent from 3 were while 1 probe and all and I eagerly envisions saying OK I'm going to go ahead and treat my 3 Bromo 1
proper and all With magnesium and IFO Easter in
hopes soaring expectations of getting this spring your reagent we wouldn't get at the problem with this Granada reagent is it's inherently unstable and can be formed in I gave you an example in our previous lecture that sows the seeds for destruction here if we take a graveyard reagents and treated with an alcohol like ethanol this is the example from the previous class I pointed out that vineyard
reagents are very strongly basic and alcohols a sufficiently acidic
that they probe me and if we take Beutel magnesium bromide and treat it with ethanol we get butane plus but that stocks magnesium bromide basically the magnesium salt magnesium Alcock side salt ethanol and sell this hypothetical green yard reagent that we would like to generate is unstable this can be formed it can be isolated it can be generated it immediately reacts with itself With the alcohol clinching the Bromyard reagents and so to come around to work around the problems like this organic
chemists will use something called protecting groups protecting group is an idea that you're going to
hide you're going to 1 part reactive part of the molecule you're going to protect them from a reagent draw from conditions that would otherwise destroyed at an existing point in your textbook they introduced 1 class of protecting groups you'll learn about moral later protecting groups that they introduce silo in a recital ethers and so the general gist of protecting and alcohol and Sisile particularly at church funeral di methyl silently there is to take your alcohol treated with a course I Lane intercommunal died Mathilde I Colorado styling is particularly popular and the basis for base that's widely used is called it is all it's a good basis for this particular reaction I guess I will heroes even the product of this reaction is Marcile ether the way we call this free-agent TB did I as chloride and then we're going to call our out got our the TB DMS Easter will write it out here as all were you actually I will write it 1st showing you the silicon breast side down on filtered futile and we also get if you wanna ride a balanced equation the losses that have made it and it is the emitters hydrochloride but again organic chemist typically don't pay
attention to these by-products of reaction now the big idea behind protecting groups is that they're easy
to put on the hike the alcohol and then they're easy to take off so before I show you a whole sequence of reactions let me show you how to take the protecting group off so we have to teeth there and I'll just write this as our old TB the AM EST few noticed me soaring my words here many organic chemists abbreviated further just like we said I validates the abbreviated further many abbreviated further as a TBS there anyway if you your team medium as eager turn your along with Detective Ural ammonium fluoride again now we get sorted into the land of the land of acronyms detective will ammonium fluoride is a big factor checked reviewable ammonium Cat Island With fluoride as an enemy and it's a source of fluoride that dissolves in organic solvents like Tetra Hydro Fiorani and fluoride wall of silicon oxygen like silicone a lot fluoride of silica other forms of really use the strong bond the silicon when we trade our TVs DMS even with the that we get back our alcohol and again organic chemists terrible about writing by-products of reactions but I will for this 1 time right after you will die a natural style fluoride as a father alright so this brings us show application of protecting troops because the reason that people want to put protecting groups onto alcohols are to sell synthetic problems and do something they couldn't otherwise so let me show you an example of doing something we couldn't otherwise we want to generate the equivalent of this green yard reagent that I just said you couldn't make so mentioned that we take 3 Bromo 1 proper all just as we did before but instead of treating it with magnesium Anita retreated with the medium as chloride is all Nano we would get it but the TBD unless ether as I've said Johnny would write it as the the TBS ether to save save rural now if which Freedom Party being DMS the I can't even that even write all those letters to the media and asked there with magnesium and I believe there now we can generate a green yard reagent that's the equivalent of the green yard reagent that we couldn't do and if we then let's say added that foreign yard reagents Bob just continue my equation over here if we imagine anything that brings Europe reagent let's say a generic he told the elder hide those writers or carving meal are primed to indicate that we're not dealing with any specific Tetonia out the high now we could generate this otherwise impossible to achieve product but but but but but but but but but and the only
thing that would be different about this product than having generated that green yard reagent that we couldn't generate is we have the TBD amassed provided that but we know what to do with that we sample late take this
and we treat with the back of him asylum group comes off of when we generated a product that we couldn't otherwise get 1 of these tremendous intellectual triumphs of organic chemistry is the ability to think backwards about reactions it's retro synthetic analysis and it's 1 of the reasons that my academic grandfather and the academic Father of the textbook the J. Corey received the Nobel Prize in chemistry and so I want to show you an example of this very important intellectual process of thinking backwards about making for Atlantic molecules and
some going to give you again a little bit of a contrived problem that gives you the flavor of the stock
synthesis of letters asking how would we synthesize the molecule 1 viable octane die all from compounds containing 4 carbon atoms a few were AusAID compounds containing 4 carbon atoms a few words but but but but but but but but but but but but but but but but and again just like in my previous example I've done this to give you sort of a small catalog of organic compounds that you can think of without necessarily saying there are figure
compounds available but since we've already seen molecules like emitters is all Ohlund and so forth are reagents that they haven't TB VMS chloride are reagents that may have many carbon atoms I will open up
catalog and safe and any reagents but that you require and Waltemeyer knowledge 1 5 octane die all isn't dead insects fair moaning and it isn't a
drug it's certainly a representative of the types of molecules that synthetic organic chemist met so of course 1 of the things is knowing what I 1 5 octane die all the it's been so I will dry
out the the structure of it and of course you have to think God there's an octane change so there's an aide carbon chain with an alcoholic the 1 position so 1 2 4 upon I 6 7 8 and alcohol at the Five Positions but no we've started to learn to recognize that different groups can come from different sorts of connections and often there are a lot lots and lots of correct ways to put together molecules were looking to build a molecule here and so we know for example since we're looking to make it from smaller pieces that we probably wanna put it together by carbon-carbon bond forming reactions alcohols could come from tones alcohols income from edition of Bromyard reagents to keep tone throughout the hides so we can imagine breaking this molecule apart and in his view that I mentioned from 30 thousand feet last time you can look at this molecule and say OK I could envision forming this carbon-carbon bond by some form of edition of inorganic metallic reagent to a carbonyl compounds in this case for mount up high I could envision formation this carbon-carbon bonds from a molecule where we add a carbon nucleophile like a green yard reagent director-general with compound 2 an elder not quite feasible perfectly good ways part molecule together both of them however involve a fragment in 1 case is that 7 carbon atoms in 1 case that's 5 carbon atoms but if I envision forming this carbon-carbon bond yields things look really really attractive we slept the molecule into 2 equal pieces my hypothetical example gave you all the way up to 4 carbons to work with and so that's a really really convenient here and so we could think in terms of retro synthetic analysis and say he a good retro synthetic disconnections would be needed to break this molecule into this more carbon green yard reagent and this war from the in London and remember this is the view from 30 thousand feet and we already know that we can make this work are being green Europe region because we know the green yard reagents containing alcohol and train yard groups are inherently unstable but now we have all of the tools that we need in our toolbox to solve this problem because we know that were clever enough to work with compounds that are equivalent to the screen yard reagent by use of protecting groups in so we can approach this problem with confidence and now work out a solution through in a forward
direction this start we
floor Bromo 1 Butte and all we protect them with the medium as chloride amid is all today get the corresponding to the media messy there but we take our TV MSC there we treated it with magnesium and there and then we add to that green yard
reagent if you've generated 1 in the laboratory typically take met metal turnings magnesium turnings but the minute drive last maybe flame the the flask you'll Edgar ether the ladder green yard created costs the magnesium turnings until the reaction starts a new generator Bromyard reagent once you've generated your yard
reagents you will immediately add to it during the day and I was due to announce you'll probably distill your view a TA will still your view now so it's nicely pure you carried out meekly as worked out with the other Jews in acid duration commitments saintly exceeds the you literally literally could do this if the chemistry stock you would go to them and ask them for all of these reagents a little short on space here I've got a crunching DMS group and now in the final step of our synthesis use simply treat this DVD units he there we see them but with the Menlo
behold new generated your 1 by opting dial all right well this is this is the way we think about
carbon chemistry we've learned a lot of reactions of them as we continue into the next chapter we're going to learn new reactions of carbon group thank you
Chemische Forschung
Stereoselektivität
Alkohol
Single electron transfer
Feuer
Kohlenstofffaser
VOC <Ökologische Chemie>
Wasser
Öl
Hydride
Magnesium
Sprödbruch
Benzoesäure
Mannose
Reaktionsmechanismus
Nebenprodukt
Methylgruppe
Vorlesung/Konferenz
Molekül
Bromide
Zunderbeständigkeit
Funktionelle Gruppe
Biosynthese
Gen notch
Krankengeschichte
Reglersubstanz
Organische Verbindungen
Fülle <Speise>
High throughput screening
Oxidschicht
Potenz <Homöopathie>
Setzen <Verfahrenstechnik>
Quellgebiet
Aluminiumhydrid
Gangart <Erzlagerstätte>
Kalisalze
Ester
Körpergewicht
Lithium
Lymphangiomyomatosis
Mikroskopie
Stereoselektivität
Wasserstand
Trennverfahren
Aktivität <Konzentration>
Kohlenstofffaser
Setzen <Verfahrenstechnik>
Gangart <Erzlagerstätte>
Natrium
Magnesium
Chemische Verbindungen
Reaktionsgleichung
Werkzeugstahl
Benzoesäure
Methanol
Reaktionsmechanismus
Ionenbindung
Chemische Bindung
Nebenprodukt
Lithium
Methylgruppe
Atombindung
Benzolring
Vorlesung/Konferenz
Biosynthese
Vimentin
Metallatom
Aldehyde
Wasser
Biogasanlage
Hydride
Altern
Spezies <Chemie>
Chemische Struktur
Reaktionsmechanismus
Ionenbindung
Nebenprodukt
Mesomerie
Chemische Bindung
Methylgruppe
Sammler <Technik>
Alkoholgehalt
Atombindung
Vorlesung/Konferenz
Funktionelle Gruppe
Reglersubstanz
Hydrierung
Einsames Elektronenpaar
Quellgebiet
Galactose
Aluminiumhydrid
Metamfetamin
Elektronische Zigarette
Methanol
Oxide
Lithium
Aluminium
Sauerstoffverbindungen
Erholung
Alkohol
Wursthülle
Diatomics-in-molecules-Methode
Aldehyde
Aluminiumhydrid
Elektronische Zigarette
Reduktionsmittel
Biskalcitratum
Alkalische Leukozytenphosphatase
Lithium
Pharmazie
Vorlesung/Konferenz
Phenylalanin-Ammoniumlyase
Spezies <Chemie>
Stereoselektivität
Digoxigenin
Oxidschicht
Säure
Aldehyde
Kohlenstofffaser
Vorlesung/Konferenz
Hydride
Alkylierung
Carboxylierung
Konvertierung
Chloride
Metallatom
Aktivierung <Physiologie>
Wursthülle
Oxidschicht
Aldehyde
Kohlenstofffaser
Organischer Halbleiter
Magnesium
Chloridion
Mischen
Säure
Lithium
Veresterung
Vorlesung/Konferenz
Terminations-Codon
Carboxylierung
Reglersubstanz
Chloride
Organische Verbindungen
Vancomycin
Potenz <Homöopathie>
Aldehyde
Gangart <Erzlagerstätte>
Aluminiumhydrid
Selenite
Säure
Lithium
Methylgruppe
Vorlesung/Konferenz
Carboxylierung
Kupfer
Carbanion
Aldehyde
Reaktivität
Kohlenstofffaser
Molekulardynamik
Betäubungsmittel
Reaktionsmechanismus
Übergangsmetall
Lithium
Methylgruppe
Atombindung
Vorlesung/Konferenz
Aluminium
Palladium
Kupfer
Chloride
Organische Verbindungen
Aktivität <Konzentration>
Wursthülle
Diatomics-in-molecules-Methode
Calciumhydroxid
Aldehyde
Eliminierungsreaktion <alpha->
Acetylen
Hydride
Lithiumiodid
Bukett <Wein>
Iodide
Nebenprodukt
Säure
Methylgruppe
Lithium
Elektronentransfer
Vorlesung/Konferenz
Funktionelle Gruppe
Glimmer
Beta-Faltblatt
Weibliche Tote
Carboxylierung
Reglersubstanz
Kupfer
Organische Verbindungen
Reaktionsmechanismus
Säure
Lithium
Vorlesung/Konferenz
Aluminiumhydrid
Lactose
Benetzung
Eliminierungsreaktion
Carboxylierung
Reglersubstanz
Mil
Derivatisierung
Chemotherapie
Sense
Oxidschicht
Kunstleder
Besprechung/Interview
Vorlesung/Konferenz
Funktionelle Gruppe
Lactose
Chemische Verbindungen
Terephthalsäure
Reglersubstanz
Lösungsmittel
Gang <Geologie>
Alkohol
Chemischer Reaktor
Kohlenstofffaser
Hühnergott
Aluminiumhydrid
Natrium
Hydride
Chemische Verbindungen
Mergel
Single electron transfer
Reduktionsmittel
Methanol
Glykosaminoglykane
Säure
Lithium
Carbonylgruppe
Gärungstechnologie
Vorlesung/Konferenz
Natriumhydrid
Funktionelle Gruppe
Carboxylierung
Stereoselektivität
Organische Verbindungen
Hydrierung
Kohlenstofffaser
Kaugummi
Setzen <Verfahrenstechnik>
Aluminiumhydrid
Taxis
Natrium
Hydride
Fluoralkene
Chemische Verbindungen
Doppelbindung
Azokupplung
Rauschgift
Mannose
Reduktionsmittel
Lithium
Krankheit
Vorlesung/Konferenz
Molekül
Funktionelle Gruppe
Hochdruckhydrierung
Aluminium
Mil
Hydrierung
Kohlenstofffaser
Kaugummi
Korken
Druckausgleich
Fluoralkene
Altern
Hexagonaler Kristall
Bukett <Wein>
Chemische Bindung
Verstümmelung
Vorlesung/Konferenz
Palladium
Platin
Sauerstoffverbindungen
Pelosol
Reglersubstanz
Tafelwein
Abfüllverfahren
Metallatom
Aktivität <Konzentration>
Stahl
Platinmetalle
Cyclin-abhängige Kinasen
Setzen <Verfahrenstechnik>
Topizität
Tank
Druckausgleich
Fluoralkene
Brillenglas
Chemotherapie
Vorlesung/Konferenz
Hochdruckhydrierung
Dictyosom
Platin
Single electron transfer
Wursthülle
Oxidschicht
Kohlenstofffaser
Vorlesung/Konferenz
Bukett <Wein>
Doppelbindung
Reglersubstanz
Kalium
Alkohol
Aktivität <Konzentration>
Schweflige Säure
Oxidschicht
Schönen
Carcinogenität
Kaliumdichromat
Wasser
Natrium
Brandsilber
Dichromate
Calcineurin
Chemotherapie
Oxide
Krankheit
Toxizität
Vorlesung/Konferenz
Chrom
Stereoselektivität
Hydrierung
Blausäure
Kohlenstofffaser
Setzen <Verfahrenstechnik>
Kernreaktionsanalyse
Taxis
Aluminiumhydrid
Selenite
Magnesium
Messing
Chemische Verbindungen
Oxygenierung
Chemotherapie
Chemische Bindung
Säure
Methylgruppe
Lithium
Vorlesung/Konferenz
Boyle-Mariotte-Gesetz
Bromide
Funktionelle Gruppe
Kupfer
Elektron <Legierung>
Wursthülle
Einsames Elektronenpaar
Ausflockung
Kohlenstofffaser
Reaktivität
Besprechung/Interview
Alphaspektroskopie
Linolensäuren
Chemische Verbindungen
Strom
Hyperpolarisierung
Chemische Struktur
Oxygenierung
Reaktionsmechanismus
Mesomerie
Chemische Bindung
Fließgrenze
Carbonylgruppe
Atombindung
Vorlesung/Konferenz
Funktionelle Gruppe
Sauerstoffverbindungen
Insel
Katalase
Additionsreaktion
Organische Verbindungen
Chemische Struktur
Hydrierung
Elektron <Legierung>
Wursthülle
Mesomerie
Reaktivität
Kohlenstofffaser
Gin
Vorlesung/Konferenz
Beta-Faltblatt
Doppelbindung
Insel
Organische Verbindungen
Elektron <Legierung>
Wursthülle
Kohlenstofffaser
Reaktivität
Quellgebiet
Gangart <Erzlagerstätte>
Alphaspektroskopie
Konvertierung
Protonierung
Spezies <Chemie>
Chemische Struktur
Reaktionsmechanismus
Thermoformen
Mesomerie
Vorlesung/Konferenz
Singulettzustand
Sauerstoffverbindungen
Reglersubstanz
Gensonde
Stereoselektivität
Wursthülle
Lithium
Vorlesung/Konferenz
Aluminiumhydrid
Selenite
Stockfisch
Alkohol
Quelle <Hydrologie>
Butyraldehyd
Kochsalz
Hope <Diamant>
Vorlesung/Konferenz
Bromide
Selenite
Magnesium
Ethanol
Chloride
Organische Verbindungen
ISO-Komplex-Heilweise
Alkohol
Silicone
Reaktivität
Base
Ether
Oktanzahl
Vancomycin
Pharmazie
Krankheit
Vorlesung/Konferenz
Molekül
Funktionelle Gruppe
Veretherung
Chloride
ISO-Komplex-Heilweise
Alkohol
Besprechung/Interview
Ammoniumverbindungen
Magnesium
Ether
Nebenprodukt
Chemische Bindung
Sekundärstruktur
Vorlesung/Konferenz
Funktionelle Gruppe
Siliciumdioxid
Insel
Sonnenschutzmittel
Organische Verbindungen
Lösungsmittel
Substrat <Boden>
Silicone
Quellgebiet
Selenite
Syntheseöl
Prolin
Katalase
Thermoformen
Valin
Ammoniumfluorid
Fluoride
Sauerstoffverbindungen
Biologisches Material
Organische Verbindungen
Nobelpreis für Chemie
Vorlesung/Konferenz
Molekül
Funktionelle Gruppe
Syntheseöl
Selenite
Chemischer Prozess
Dampfschlepper
Stockfisch
Organische Verbindungen
Octane
Vorlesung/Konferenz
Molekül
Kohlenstoffatom
Chemische Verbindungen
Dampfschlepper
Biosynthese
Calcineurin
Rauschgift
Chloride
Organische Verbindungen
Trauma
Biskalcitratum
Setzen <Verfahrenstechnik>
Octane
Vorlesung/Konferenz
Molekül
Weibliche Tote
Kohlenstoffatom
Carbanion
Metallatom
Alkohol
Screening
Antagonist
Wursthülle
Kohlenstofffaser
Setzen <Verfahrenstechnik>
Syntheseöl
Selenite
Chemische Verbindungen
Werkzeugstahl
Bindegewebe
Chemische Struktur
Thermoformen
Chemische Bindung
Fließgrenze
Carbonylgruppe
Octane
Gin
Vorlesung/Konferenz
Molekül
Funktionelle Gruppe
Kohlenstoffatom
Chloride
Metallatom
Substrat <Boden>
Vorlesung/Konferenz
Selenite
Magnesium
Flamme
Chemische Forschung
Stockfisch
Hecklader
Säure
Formylgruppe
Vorlesung/Konferenz
Gangart <Erzlagerstätte>
Famotidin
Funktionelle Gruppe
Biosynthese
Chemische Forschung
Carboxylate
Kohlenstofffaser
Oxide
Aldehyde
Kohlenstoffgruppe
Kernreaktionsanalyse
Kohlenstofffaser
Computeranimation
Säure
Mannose
Destillateur
Chemische Struktur
Alkohole <tertiär->
Brandsilber
Atom
Syntheseöl
Redoxsystem

Metadaten

Formale Metadaten

Titel Lecture 04. Reactions and Protecting Groups.
Serientitel Chemistry 51C: Organic Chemistry (Spring 2012)
Teil 04
Anzahl der Teile 19
Autor Nowick, James
Lizenz CC-Namensnennung 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen.
DOI 10.5446/19408
Herausgeber University of California Irvine (UCI)
Erscheinungsjahr 2012
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Chemie
Abstract UCI Chem 51C Organic Chemistry (Spring 2012) Lec 04. Organic Chemistry -- Reactions and Protecting Groups -- Instructor: James S. Nowick, Ph.D. Description: This is the third quarter course in the organic chemistry series. Topics covered include: Fundamental concepts relating to carbon compounds with emphasis on structural theory and the nature of chemical bonding, stereochemistry, reaction mechanisms, and spectroscopic, physical, and chemical properties of the principal classes of carbon compounds. Index of Topics: -3:09 Carboxylic Acids and LiAlH4 -9:07 DIBAL-H -14:59 Multiple Equivalents of Organometallic Reagents -18:18 Organocuprate Reagent -22:11 Chemoselectivity -26:14 Reducing Carbonyls and Alkenes -30:48 Oxidizing Agents -33:31 Regioselectivity -36:10 Resonance -40:00 Enones and Nucleophiles -41:45 Enolate Anion -44:15 Tautomerization -45:53 Protecting Groups -50:40 Taking the Protecting Groups Off -56:32 Synthesizing -1:05:33 Corrections

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