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Topic: Cyclization Reaction  (Read 9680 times)

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Offline Nescafe

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Re: Cyclization Reaction
« Reply #15 on: August 12, 2014, 03:17:36 PM »
After giving it some thought, melting it does not seem like the best choice as I anticipate it will just polymerize rather than cyclize. At the moment I am trying to generate the acid chloride under high dilution conditions.

Correct me if I am wrong but melting it would basically mean heating a concentrated sample (no solvent) so it will just polymerize

Offline discodermolide

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Re: Cyclization Reaction
« Reply #16 on: August 12, 2014, 03:34:52 PM »
I have quite often made lactams by this method, it works rather well.
Try some in a MPt tube and see what happens.
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Offline Nescafe

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Re: Cyclization Reaction
« Reply #17 on: August 12, 2014, 03:38:33 PM »
I shall try it out then. Sorry, what is a MPt tube? I am guessing a melting tube but when I looked Sigma I could not find such an item.

Offline discodermolide

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Re: Cyclization Reaction
« Reply #18 on: August 12, 2014, 03:42:05 PM »
Just a melting point tube. Heat it to the MPt, leave it for 5 minutes, cool it and re-take the MPt. Then you will see if anything has happened.
https://www.youtube.com/watch?v=S-GGiTxjYo8
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Offline Nescafe

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Re: Cyclization Reaction
« Reply #19 on: August 12, 2014, 03:52:27 PM »
I will definitely give this a go and report back, quick question, so at the moment both the amine and the carboxylic acid functionality are protected with acid labile groups. I was thinking of doing a global deprotection with 0.1M HCl in dioxane, vac it off and then try melting. i can not do a work up since it will not leave my aqeous layer. Do I have any other options? I really want to try the melting idea.

If I neutralize with base I can not vac that off, can I just try melting with the base present? Also please keep in mind I have 30mg of this stuff :P

Offline discodermolide

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Re: Cyclization Reaction
« Reply #20 on: August 12, 2014, 04:02:44 PM »
The HCl salt will not cyclise. Try adding triethylamine , enough to neutralize the HCl salt.
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Offline Nescafe

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Re: Cyclization Reaction
« Reply #21 on: August 12, 2014, 05:34:54 PM »
Neutralize with TEA and then try to melt with the TEA present?

Offline discodermolide

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Re: Cyclization Reaction
« Reply #22 on: August 12, 2014, 07:16:34 PM »
Yes
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Offline Nescafe

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Re: Cyclization Reaction
« Reply #23 on: August 22, 2014, 10:05:06 PM »
You sir are a wizard!

That worked, not the cleanest reaction I have ever done but better than anything else I tried. There is a peak at 3.0-3.05 (it is in CDCl3) which is a broad singlet that integrates to 0.5, I just can not seem to figure out what it is. Granted my NMR sample was very concentrated but I am not sure if I dilute it if that will be cheating if it goes away or integrates to like 0.1. This compound needs to be at least 95% pure. I can try recolumning it but I barely have any left and it is hard to make. Any idea what it might be, I have no alcohols or anything of that sort in the SM, there is no SM left actually and it is one spot by UV. Stained with multiple things and nadaa so I am not sure where it is coming from. The solvent (CDCl3) is also relatively new.

Thanks!

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Re: Cyclization Reaction
« Reply #24 on: August 22, 2014, 10:20:03 PM »
Does it exchange with D2O?
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