Iron catalysis for biaryl coupling and ether cleavage reactions
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| Number of Parts | 163 | |
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| License | CC Attribution - NoDerivatives 4.0 International: You are free to use, copy, distribute and transmit the work or content in unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor. | |
| Identifiers | 10.5446/50414 (DOI) | |
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00:00
IronKupplungsreaktionArylChemical reactionFunctional groupTransformation <Genetik>River sourceTiermodellIronMeeting/Interview
00:13
Transformation <Genetik>Functional groupNoble gasTransportMetalElektronentransferProcess (computing)Synthetic oilMetabolismChemical reactionRhodiumRiver sourceIronPlatinMoleculePalladiumIonenbindungPlant breedingIslandLecture/ConferenceMeeting/Interview
01:02
Chemical reactionFunctional groupIronMoleculeIonenbindungIslandReducing agentTransformation <Genetik>Chemical experimentMeeting/Interview
01:14
Transformation <Genetik>IronMultiprotein complexMetalReducing agentMeeting/InterviewLecture/Conference
01:31
Electrical mobilityActivity (UML)Reducing agentMultiprotein complexGesundheitsstörungIslandIronFunctional groupDrawing
01:47
Functional groupMoleculeSetzen <Verfahrenstechnik>Animal trappingMeeting/InterviewLecture/Conference
02:04
Functional groupAnimal trappingProcess (computing)IronMeeting/InterviewLecture/Conference
02:17
IronProcess (computing)Meeting/InterviewLecture/Conference
02:30
RapidAlcoholSeparation processChlorideIronEthylgruppeMagnesium chlorideWursthülleChemical reactionMeeting/InterviewChemical experiment
03:10
Chemical reactionAgeingIngredientMixtureChemical experiment
03:40
Chemical experiment
03:51
Chemical experiment
04:04
IronChemical experiment
04:22
SolutionMeatGrignard-ReaktionIronAddition reactionMolar volumeChlorideChemical reactionChemical experiment
04:44
AgeingMagnesium chlorideColourantEthylgruppeAdamantaneSetzen <Verfahrenstechnik>SpeciesChemical experiment
05:09
SpeciesActivity (UML)SolutionProcess (computing)Chemical experiment
05:23
Process (computing)Aqueous solutionChemical reactionAmmonium chlorideSolutionChemical experiment
05:35
Gene expressionDiethyl etherExtractChemical experiment
05:48
Chemical experiment
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Chemical reactionChemical experiment
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Chemical reactionDünnschichtchromatographieChemical experiment
06:41
EugenolChemical reactionKupplungsreaktionStarvation responseActivity (UML)
06:56
KupplungsreaktionChemical reactionActivity (UML)Starvation responseRedoxChemical experiment
07:25
AcetylationIronSpeciesIsotopenmarkierungActivity (UML)WursthülleChemical structureChemical experiment
07:40
SpeciesVinylverbindungenIronActivity (UML)LigandChemical experiment
07:52
OxideChemical structureSubstitutionsreaktionOctane ratingChemical reactionAddition reactionVinylverbindungenKupplungsreaktionIronSpeciesGrignard-ReaktionChemical experiment
08:25
Chemical reactionColourantEmission spectrumGrignard-ReaktionIronAcetylationChemical experiment
08:44
Chemical reactionMixtureColourantBody weightIronStickstoffatomSolventAcetylationProgram flowchartChemical experiment
09:07
StickstoffatomMixtureChemical experiment
09:22
Pitch (resin)Chemical experiment
09:34
Chemical reactorChemical experiment
09:47
ConcentrateChemical reactionDerivative (chemistry)Molar volumeChemical experiment
10:21
Chemical reactionChemical experiment
10:35
Chemical reactionColourantChemical experiment
10:47
BromideSolutionChemical reactionChemical experiment
11:08
Chemical reactionDrop (liquid)Ion transporterChemical experiment
11:24
Drop (liquid)ColourantOxideAddition reactionChemical reactionIronSpeciesPotassium carbonateSolutionGesundheitsstörungIceCell divisionChemical experiment
12:18
EssigsäureethylesterAddition reactionExtractSolutionChemical reactionMixing (process engineering)Potassium carbonateChemical experiment
12:48
Multiprotein complexChemical reactionColumn chromatographyIronOrganische ChemieActivity (UML)BiosynthesisIonenbindungHope, ArkansasLeft-wing politicsCarbon (fiber)Chemical experiment
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IonenbindungChemical reactionMoleculeAlcoholNaturstoffDiagram
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NaturstoffEugenolAlcoholMoleculeLecture/ConferenceComputer animation
Transcript: English(auto-generated)
00:09
Hello, my name is Axel Jacobi. I had a research group at the Department of Chemistry at the University of Regensburg. My group is interested in the development of catalytic transformations. One of the main objectives in our group is the use of iron as a catalyst metal.
00:24
Iron is a very attractive metal as it's very, very cheap and can be found in many, many sources on our planet. So it is not surprising that nature does actually use iron as a catalyst in many, many transformations. For instance, in the metabolism of small molecule, in the transport of small molecule, and also in electron transfer processes.
00:43
On the other hand, it is quite surprising to see that there's only a handful of iron-catalyzed processes in man-made synthetic transformations. While most of the challenging reactions are still being exerted with the use of very, very toxic and noble metals such as palladium, platinum, and rhodium.
01:01
Over the past two or three years, my group has been looking into reactions where we try to activate a rather sluggish and very, very strong single bond in these molecules by the use of an iron catalyst. And we have been, alongside other group, we found that low valent reduced iron complexes are very, very competent in these transformations.
01:24
And we simply generate these low valent reduced metals by the reduction of simple iron plus three salts, which can be commercially obtained for just one euro per mole in the presence of various reductants. Where we undergo this activation here, we generate in the first stage
01:44
such a complex where we have two polarized moieties on the iron complex. And now we have two opportunities to take advantage of these moieties. One would be the nucleophilic trapping of one of the moieties and the other then, of course, an
02:01
electrophilic trapping with a suitable electrophile. And this would give rise to the formation of two organic molecules, one being the nucleophilic trapping product and the other being the electrophilic trapping product. And my group will just in a second show you exactly two
02:20
applications where we take advantage of an iron catalyzed process to generate selectively either this or this product in a very, very practical and cheap fashion. Hi, my name is Dominik Gertner, and I want to show you an operational, simple and rapid method for de-addilation of alcohols. For an example, I picked up
02:42
O-L-L-Eugenone. Our de-addilation reaction takes place with an iron chloride catalyst, in our case iron 3 chloride, with one mole percent.
03:05
Our reducing reagent is commercial ethyl magnesium chloride. We're using one equivalent and the reaction is carried out in M-xylene and
03:21
THF mixture at room temperature in less than one hour. And our product is the de-alloyated product called eugenol, an ingredient of carnations. And because our pre-catalyst is hygroscopic, we have to weigh it in the glove box. Now here
04:16
we have our pre-catalyst, iron 3 chloride, and now we're gonna solve it in THF.
04:31
Now here I've prepared a solution of the O-L-Eugenol in M-xylene, and now I'm adding the iron chloride solution to the
04:41
substrate solution. The reaction only starts after the addition of the Grignard reagent. We're using a two molar ethyl magnesium chloride in THF.
05:04
I'm just adding it now. The color change you'll see indicates the formation of the active catalyst species.
05:25
After one hour, the de-alloyation process is complete and we can now quench the reaction with an aqueous ammonium chloride solution.
05:42
Now the de-alloyated product can easily be isolated via extraction with diethyl ether. The product will be in the organic layer.
06:12
Now I'm shaking the reaction mixture.
06:22
Take again the organic layer. Now the reaction results can be shown in a TLC analysis.
06:43
Now, under the UV light, you can see the reaction was successful. On the left side, you can see the adduct, the O-L-Eugenol, and on the right side, the eugenol. Hello, my name is Samit Gulag. I'm a third year PhD student working on the field of iron-catalyzed cross-coupling reactions.
07:02
Today, I want to show you an experiment which highlights the simplicity and the effectiveness of iron-catalyzed bioral coupling reactions. During the last year of my PhD, I discovered a new mode of activation in reactions with chlorosilanes, which I draw already here. Chlorosilanes are very simple and easy to prepare, but are rather unreactive for cross-coupling reactions. In this reaction,
07:26
we use iron as catalyst, this reduced iron species. This, we are forming in-situ from iron acetyl acetenate, in this case, which is commercially available.
07:41
This reduced iron species has a labile ligand sphere, so it can coordinate to the vinyl group. And this is exactly the effect which we want to use for the activation of chlorosilanes. And if we look at this structure, we can see this chlorosilane. It has a vinyl group, so the reduced iron species can coordinate there, and then it can do a fast oxidative addition,
08:07
which leads to this structure. And after addition of more of the Grignard reagent, we form this nicely substituted styrene derivative products, which are carrying this vinyl group, which we can use for further reactions like
08:24
oxidations, reductions, or also CC coupling reactions like HECC reaction. And we can also visually follow this reaction. We start here with a red color. It's the color of the iron acetyl acetenate dissolved in THF. Then we reduce it with the Grignard reagent, and then we come to this
08:41
typical brown color for this active catalyst. And then after oxidative addition, we see the yellow color. Okay, now let's see how the reaction works. I already weighed in the iron pre-salt. It's the iron acetyl acetenate 3, which has this typical red color.
09:02
And I will dissolve it now in a solvent mixture of THF and NNP. We are doing everything in the nitrogen atmosphere. I take now around four milliliters of the solvent mixture. I turn on the
09:29
magnetic stirrer.
09:40
When it's dissolved, I take one milliliter out of it and put it into my reaction vessel. Now I put the
10:03
magnetic stirrer under the reaction. Now I dilute it to the reaction concentration of around 0.2 molar. Now I will add the starting material, the chloro-styrene. It's a chloro-styrene derivative.
10:29
Exactly one millimole with this Hamilton syringe. Now I will add it into my reaction.
10:42
And you will see that there's no color change. And now I will add the phenylmagnesium bromide with the syringe pump. Over 40 minutes. And we will now take exactly
11:00
1.1 equivalents out of the phenylmagnesium bromide solution. I plug this in the reaction.
11:23
Now I will start the syringe pump. And with every drop we see that we get dark color. It shows us that the reduced iron species is formed and directly
11:46
the typical yellow color of the oxidized species. Now after one hour the reaction is done. We see that from the typical black color
12:00
it shows us that no oxidative addition is taking place now. And as you can see here, we have this black, nice color. And now we will add potassium carbonate solution into this reaction to quench it and then
12:20
do a simple extraction by addition of ethyl acetate. I will mix this solution
12:41
also like this. Now after quenching with potassium carbonate solution and extraction with ethyl acetate we now can do GC analysis from the reaction mixture or can clean up the product by simple column chromatography.
13:01
Well, I hope we could show you that reduced iron complexes have a high activity as catalysts in organic synthesis. And we've exemplified this today by two reaction classes. One where we make a carbon-carbon single bond to make this fancy bi-aromativ here on the left hand side. And on the other hand where we break a carbon-oxygen
13:22
single bond to de-alloyate, that is to de-functionalize this molecule to release the free alcohol which is a natural product called eugenol. Thanks for your interest in our research. Goodbye.