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Topic: A question on protection  (Read 1864 times)

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Offline Urbanium

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A question on protection
« on: March 24, 2014, 06:28:07 AM »
Hello,

I'm doing a protection of secondary amine in thiomorpholine ring, and it's the first time in general I'm doing a protection of an amino group. I've checked in papers if there is some procedure for this particular case, but I wasn't able to find it.

In your opinion, is Boc a good protective group in this case? My substrate is a secondary amine incorporated in the ring, and I'm not sure if classic Boc procedures will work here).

 Which molar ratios of substrate vs. Boc2O vs. DMAP should I use in this case (i.e. is there some rule of thumb for molar ratios when it comes to Boc protection)?

Offline sjb

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Re: A question on protection
« Reply #1 on: March 24, 2014, 08:45:27 AM »
Hello,

I'm doing a protection of secondary amine in thiomorpholine ring, and it's the first time in general I'm doing a protection of an amino group. I've checked in papers if there is some procedure for this particular case, but I wasn't able to find it.

In your opinion, is Boc a good protective group in this case? My substrate is a secondary amine incorporated in the ring, and I'm not sure if classic Boc procedures will work here).

 Which molar ratios of substrate vs. Boc2O vs. DMAP should I use in this case (i.e. is there some rule of thumb for molar ratios when it comes to Boc protection)?

What are you hoping to protect this against?

Offline Urbanium

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Re: A question on protection
« Reply #2 on: March 24, 2014, 09:23:44 AM »
Well I can't quite say that, only that I'm doing a nucleophile displacement on sulfur, and there is a very good chance the secondary amine in thiomorpholine would react, so I need to protect it somehow in order to restore it later.

Offline TheUnassuming

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Re: A question on protection
« Reply #3 on: March 24, 2014, 09:31:54 AM »
A simple boc protection should work just fine. 
I typically use catalytic DMAP with around 1.25 equiv of boc anhydride.  I recently did this on a non-aromatic heterocyclic amine and it worked just fine.
When in doubt, avoid the Stille coupling.

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