I tried the method mentioned in the article above. I started with 5g of methyl-3-amino-2-thiophenecarboxylate and decarboxylated it like mentioned in the article. After the last step (evapôration of the solvent), I just got 0,2g of the product left and after the tlc analysis, I could see that the end product (which is supposed to be 3-aminothiophene) still contains methyl-3-amino-2-thiophenecarboxylate (starting material). Does anyone know a better method for decarboxylation of methyl-3-amino-2-thiophenecarboxylate to get 3-aminothiophene?
I tried the method mentioned in the article above. I started with 5g of methyl-3-amino-2-thiophenecarboxylate and decarboxylated it like mentioned in the article. After the last step (evapôration of the solvent), I just got 0,2g of the product left and after the tlc analysis, I could see that the end product (which is supposed to be 3-aminothiophene) still contains methyl-3-amino-2-thiophenecarboxylate (starting material). Does anyone know a better method for decarboxylation of methyl-3-amino-2-thiophenecarboxylate to get 3-aminothiophene?
Good find pgk! OP, this also means the bench stability of this compound could be low. The decarboxylation also takes places at high temperature, which could mean that this procedure is poorly suited for what you are doing.
Perhaps the HCl salt is stable? For either during the reaction or storage of the product. Its very common to see that.
Good find pgk! OP, this also means the bench stability of this compound could be low. The decarboxylation also takes places at high temperature, which could mean that this procedure is poorly suited for what you are doing.
Perhaps the HCl salt is stable? For either during the reaction or storage of the product. Its very common to see that.
In the US patent 2278762-(1942), is clearly stated that: “free amines of heterocyclic sulfur compounds are highly unstable toward oxidation and polymerization in themselves, as to make their manufacture and any industrial use impractical”. Thus, it’s not a bad idea to repeat the procedure under slight nitrogen flow and adding 1-2% of an antioxidant, such as BHT or BHA.
In the US patent 2278762-(1942), is clearly stated that: “free amines of heterocyclic sulfur compounds are highly unstable toward oxidation and polymerization in themselves, as to make their manufacture and any industrial use impractical”. Thus, it’s not a bad idea to repeat the procedure under slight nitrogen flow and adding 1-2% of an antioxidant, such as BHT or BHA.
Ah well you can at least buy the Boc-protected thiophene and use it to (very) easily make the aminothiophene instead of doing all this other difficult running around. I'm rather surprise that there will be conditions that can handle a free amine but not a Boc group
Ah well you can at least buy the Boc-protected thiophene and use it to (very) easily make the aminothiophene instead of doing all this other difficult running around. I'm rather surprise that there will be conditions that can handle a free amine but not a Boc group
If you do a Curtius rearrangement be careful! It can be exothermic to the point of explosiveness.
Why won't your prof let you use N-Boc-3-aminothiophene? Its a little pricey at $45 a gram, but once you fail a few times doing other ways you've blown right past that price point.
If you do a Curtius rearrangement be careful! It can be exothermic to the point of explosiveness.
Why won't your prof let you use N-Boc-3-aminothiophene? Its a little pricey at $45 a gram, but once you fail a few times doing other ways you've blown right past that price point.
I am going to use 3-aminothiophene for direct arylation and my professor said that Boc protected aminothiophene won't be stable in the conditions we are going to use. Thank you everyone for the reply. Currently I am also watching videos and reading a book about laboratory techniques for organic chemistry because I am a student of applied engineering and I don't have a lot of lab experience for organic synthesis. on monday I will try the same procedure (for decarboxylation) under supervision of my professor to see whether or not I made a mistake during the lab session.
I am going to use 3-aminothiophene for direct arylation and my professor said that Boc protected aminothiophene won't be stable in the conditions we are going to use. Thank you everyone for the reply. Currently I am also watching videos and reading a book about laboratory techniques for organic chemistry because I am a student of applied engineering and I don't have a lot of lab experience for organic synthesis. on monday I will try the same procedure (for decarboxylation) under supervision of my professor to see whether or not I made a mistake during the lab session.
An Easy Synthesis of 3-Amino- and 3-Nitrothiophene, Synthetic Communications, (1995), 25(23), 3729-3734 http://www.tandfonline.com/doi/abs/10.1080/00397919508011446
An Easy Synthesis of 3-Amino- and 3-Nitrothiophene, Synthetic Communications, (1995), 25(23), 3729-3734 http://www.tandfonline.com/doi/abs/10.1080/00397919508011446
You can buy thiophene-3-carboxylic acid and do a Curtius-rearangement to the thiophene-3-isocyanate, then boil this in toluene with benzylalcohol, then you will get the Cbz-protected 3-aminothiophene without having to handle the sensitive free aminothiophene.
You can buy thiophene-3-carboxylic acid and do a Curtius-rearangement to the thiophene-3-isocyanate, then boil this in toluene with benzylalcohol, then you will get the Cbz-protected 3-aminothiophene without having to handle the sensitive free aminothiophene.
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Perhaps the HCl salt is stable? For either during the reaction or storage of the product. Its very common to see that.
Perhaps the HCl salt is stable? For either during the reaction or storage of the product. Its very common to see that.
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Thus, it’s not a bad idea to repeat the procedure under slight nitrogen flow and adding 1-2% of an antioxidant, such as BHT or BHA.
Thus, it’s not a bad idea to repeat the procedure under slight nitrogen flow and adding 1-2% of an antioxidant, such as BHT or BHA.
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Why won't your prof let you use N-Boc-3-aminothiophene? Its a little pricey at $45 a gram, but once you fail a few times doing other ways you've blown right past that price point.
Why won't your prof let you use N-Boc-3-aminothiophene? Its a little pricey at $45 a gram, but once you fail a few times doing other ways you've blown right past that price point.
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http://www.tandfonline.com/doi/abs/10.1080/00397919508011446
http://www.tandfonline.com/doi/abs/10.1080/00397919508011446
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