Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: blackcat on September 27, 2019, 10:22:07 AM
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In your professional life (e.g. PhD or professional workers), which organic reaction is most important to you?
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It depends on the project, not possible to generalize.
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Substitutions involving the trifluoromethanesulfonyl group leaving have helped me twice at different points in my career.
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Substitutions involving the trifluoromethanesulfonyl group leaving have helped me twice at different points in my career.
I guess what you did is using triflate as pseduo-halide in cross-coupling reaction, right?
For simple SN2 reaction people may use OTs group as it is way cheaper.
Triflate reactivity in between iodine and bromine.
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I used trimethylsilyl trifluoromethanesulfonate and tetrabutylammonium iodide in place of TMSI. I was trying to remove the methyl ester groups from a very labile phosphate ester. TMSI is not the easiest compound with which to work.
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I used trimethylsilyl trifluoromethanesulfonate and tetrabutylammonium iodide in place of TMSI. I was trying to remove the methyl ester groups from a very labile phosphate ester. TMSI is not the easiest compound with which to work.
Ok, I see. Please confirm my logic here:
TMSI is very reactive and hard to handle and you wanna make it in situ. TMSI in this case serves as a very mild deprotecting agent. For your methyl phosphate ester, the reaction with TMSI will give TMS phosphate and methyl iodide.
Is this correct?
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Yes; if memory serves me, we ran the reaction at -30 °C in DCM. Once you have a trimethylsilyl phosphate ester, that sort of compound is very easily solvolyzed in alcohols or in water, sometimes in the presence of a weak base.
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The thiol-ene reaction. I have used it successfully for the last 3 companies I've worked at, and if the desired properties are met of my latest batch of compounds, my current company as well.
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The thiol-ene reaction. I have used it successfully for the last 3 companies I've worked at, and if the desired properties are met of my latest batch of compounds, my current company as well.
Yup, this is really a versatile reaction, which can be used for crosslinking/polymerization. My colleagues for postdocs use this reaction a lot.
By the way, I think thiol-ene reaction is effected by AIBN or photoinitiator, right? Any other possible choice?
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synthesis of amides using pentafluorophenyl esters are a reaction i do all the time
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synthesis of amides using pentafluorophenyl esters are a reaction i do all the time
This chemistry relies mainly on the easy leaving of pentafluorophenoxide group, is this true? Did I miss anything here?
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Reactions I’ve done a lot of: making difficult amides in every way imaginable.
More broadly, I’d say the thing that has saved me the most in reactions I’ve had a hard time with are phase transfer catalysts, and having access to the Starks PTC text.
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synthesis of amides using pentafluorophenyl esters are a reaction i do all the time
This chemistry relies mainly on the easy leaving of pentafluorophenoxide group, is this true? Did I miss anything here?
yeah that's right, it's a great way of making amides as purification is normally really easy (no concerns about excess coupling reagent) and pentafluorophenyl esters are extremely stable and can be stored at room temperature in air for months or years with no degradation like you might expect for succinamides or acid chlorides
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Right now, Suzuki, Ullmann, and Buchwald couplings. I do these every day.
I'll say one thing. I do not like Ullmann couplings. Dirty, harsh, annoying to work with. Some reactions go fine, others need a constant feeding with catalyst and ligand.
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Right now, Suzuki, Ullmann, and Buchwald couplings. I do these every day.
I'll say one thing. I do not like Ullmann couplings. Dirty, harsh, annoying to work with. Some reactions go fine, others need a constant feeding with catalyst and ligand.
Agreed. I have done Ullmann a lot (for C-I and N-H coupling) in my Master degree. It is always a black mass. But good stuff is obtained after column chromatography
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The thiol-ene reaction. I have used it successfully for the last 3 companies I've worked at, and if the desired properties are met of my latest batch of compounds, my current company as well.
Yup, this is really a versatile reaction, which can be used for crosslinking/polymerization. My colleagues for postdocs use this reaction a lot.
By the way, I think thiol-ene reaction is effected by AIBN or photoinitiator, right? Any other possible choice?
Yes, some kind of radical generator. I have mostly used AIBN thermal initiation, but some use photo-initiators successfully. Supposedly, you can just use UV light alone at the appropriate wavelength and intensity to initiate, but I have never tried that.
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Yes, plain UV works excellently. Its not exactly a stable mixture as it is. If you leave them in the dark then autopolymerization will occur between primary thiols and alkenes.