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nleslie321
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Deprotection of N-benzyl piperidine compound
So im having trouble with deprotection of a N-benzyl group on a piperidine based compound. Im using 10% Pd/C and ammonium formate in methanol for
20hrs using Catalystic transfer hydrogenation. Should i be doing it in an acetic environment or not? Is 20hrs too much?
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njl
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What exactly is the substrate? What problem are you having? Is there any cleavage? How are you testing the product? Maybe you could try a different
reduction method like Zn/HCl. Can you link the procedure that you're working from?
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stoichiometric_steve
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You need to list the EXACT reaction conditions.
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Sigmatropic
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Amines can poison the Pd/C cat, you could try adding acid (acetic or hydrochloric).
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nleslie321
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I only have TLC to monitor reaction i dont have access to any equipment to test it as of yet. Im saving to buy a IR spec or raman spec. Ill find the
paper and link it when i have a spare 15min.
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stoichiometric_steve
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Not much use if you don't tell us what exactly YOU did.
I'm guessing you're using straight MeOH, not a mixture of MeOH:H2O 9:1?
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njl
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Telling us what the substrate is would be a pretty good start...
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stoichiometric_steve
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There's usually a reason why 
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njl
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@steve Given the context I figured this was probably on the sketchier side of things, but I want to see where this is going just because OP seems to
have access to some interesting stuff 
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nleslie321
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Sorry ive been flat out at work. Its benzyl fentanyl and im trying to make some unregulated analogues not to ingest but just out of interest. Ive been
trying to do the second last step in the original janssen fentanyl synthesis which is removing the N-benzyl group. Then ill have the compound i want
to start experimenting with. Im just not having luck using textbook methods. Any help would be appreciated. I used straight methanol and Pd/C 10% plus
ammonium formate to hydrogenate benzyl fentanyl. Benzyl fentanyl is basically inactive by the way and not scheduled here. Im making sure to stay
within the law with all my chemistry.
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nleslie321
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Yes i do have access to just about anything the only restriction is money lol a lot of good stuff is very expensive.
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Tsjerk
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Why don't you protect the piperidone directly with 2-phenyl ethylbromide? Then you don't have to deprotect anything.
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nleslie321
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Because im starting with N-benzyl-4-piperidone and i dont want fentanyl as the end product. I specifically got N-benzyl-4-piperidone as the starting
product for this reason as it seemed a lot simpler to remove a N-benzyl group than a phenethyl group and the fact that N-phenethyl-4-piperidone is
restricted. My goal is to experiment making some new analogues that are not scheduled.
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njl
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So right now you have an unregulated and inactive compound, which is only inactive due to the benzyl group, and you want to remove that benzyl group
to have straight fentanyl?
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nleslie321
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No i want to make some unregulated analogues not normal fentanyl.
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Tsjerk
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You never mentioned that N-phenethyl-4-piperidone is restricted in your area. You neither mentioned which analogues you want to make. With little
information you gain little information. If your project is legal, just give all the information needed to answer your questions.
I guess you tried something like this?.
How did you prepare the N-benzyl? Or did you buy it?
[Edited on 24-2-2020 by Tsjerk]
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njl
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How pure was the N-benzyl-4-Piperidone? If you made it yourself maybe there is a contaminant destroying your catalyst. How much are you willing to
experiment with? It might be worth it to take a few small samples and try various conditions to see what works. Also, paper please!
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SWIM
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We really need a new thread on here: "Piperidine based chemistry that doesn't destroy people's lives"
I'm gettin' tired of every other piperidine thread turning out to be like this one.
Especially since the average poster starts about three threads before he/she works up the balls to actually admit to what the project is.
Do you think occultist sites have similar problems?
"No, I'm just trying to raise Satan from the depths of hell for purely academic interest. I really don't plan on letting him wash over the earth like
a red tide and destroy humanity. I'll be keeping him safe in a pentacle... Oh by the way, in a totally unrelated question, do you know how to free
Satan from a pentacle so he can wash over the earth like a red tide and destroy all humanity?"
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nleslie321
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Yes i did that exact reaction you linked. The N-benzyl-4-piperidone is from sigma and other chemicals all bought from well known chemical supply
companies. Heres the paper-
"Synthesis and biological evaluation of some novel 1-substituted fentanyl analogs in Swiss albino mice" Shiv Kumar YADAV,
Chandra Kant MAURYA, Pradeep Kumar GUPTA, Ajai Kumar JAIN, Kumaran GANESAN, Rahul BHATTACHARYA.
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Tsjerk
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Strange.. Do you have some compound you can test the Pd on?
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nleslie321
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So ive got 2g of 10% Pd/C and 20g of 5% Pd/C im pretty sure the 10% Pd/C is good but i haven't tested it on anything else. The 5% Pd/C is definitely
good as ive used it for other things. As far as ive researched 5% isnt strong enough to debenzylate the compound. Ive not tried using H2 instead of
ammonium formate but i cant see why that would make any difference.
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Tsjerk
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I can't imaging why 10% would work any different than 5% would, besides it being twice as slow. If your 5% works; I would use that.
Please report on the use of the 5%. If that doesn't work I would contact Sigma about the acidity of their product. If you don't care you can add a
dash of glacial acetic acid to the reaction.
Or your ammonium formate might be a bit basic, how did you get that?
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nleslie321
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Hmmm ok so if i use 5% Pd/C i should run it twice as long. I got the ammonium formate off ebay from memory ill check when i get home.
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Tsjerk
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I don't think the difference between 5% and 10% is exactly linear, but it is probably a good guess.
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Chemi Pharma
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Quote: Originally posted by nleslie321  | | So ive got 2g of 10% Pd/C and 20g of 5% Pd/C im pretty sure the 10% Pd/C is good but i haven't tested it on anything else. The 5% Pd/C is definitely
good as ive used it for other things. As far as ive researched 5% isnt strong enough to debenzylate the compound. Ive not tried using H2 instead of
ammonium formate but i cant see why that would make any difference. |
If You can not trust in your Pd/C, and since it's a very expensive catalyst, why don't you try the hydrogenolysis of your N-Benzyl piperidine with
magnesium powder and ammonium formate instead?
I'm attaching an study about this method at hydrogenolysis of N-Benzylated compounds using just magnesium powder, ammonium formate, ethylene glycol
and a conventional microwave oven. Time of reaction: less than 03 minutes. Worth a read!
[Edited on 25-2-2020 by Chemi Pharma]
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