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Topic: Acylation of a benzenesulfonyl protected azaindole.  (Read 2606 times)

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Offline zuriel

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Acylation of a benzenesulfonyl protected azaindole.
« on: April 16, 2013, 05:54:46 AM »
Hi everyone,

I'm looking to know if anyone has any experience/advice.
I've protected 7-azaindole with a benzenesulfonyl protecting group and now I want to acylate at the C-3 position.
A paper I have recommends uding 5 eq. of Aluminium Trichloride and 5 eq. of the acylating agent (oxalyl chloride in this case).

I can't find any information online on whether aluminium trichloride will affect the benzenesulfonyl group in any way so I'm wondering does anyone here have any idea?

Thanks.  :)

Offline g-bones

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Re: Acylation of a benzenesulfonyl protected azaindole.
« Reply #1 on: April 17, 2013, 09:04:06 PM »
might be tough with an EWG on your nitrogen.  Not sure about the inherent selectivity of azaindole is but, with indole itself, you don't need to put a protective group on nitrogen.  Just stir up indole with oxalyl chloride and it should go directly to the 3-substituted product.

See: http://pubs.acs.org/doi/pdf/10.1021/ja077190z

hope this helps

Offline BobfromNC

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Re: Acylation of a benzenesulfonyl protected azaindole.
« Reply #2 on: May 03, 2013, 01:36:46 PM »
I would also suggest JOC, 2002, 67, 6226-6227, it is Titled:

An Effective Procedure for the Acylation of Azaindoles at C-3

"Conditions for attachment of acetyl chloride, benzoyl chloride, and chloromethyl oxalate to the 3-position of 4-, 5-, 6-, or 7-azaindoles were explored. Best results were achieved with an excess [3-5 eq] of AlCl3 in CH2Cl2 followed by the addition of an acyl chloride at room temperature. "

http://pubs.acs.org/doi/abs/10.1021/jo020135i?journalCode=joceah&quickLinkVolume=67&quickLinkPage=6226&selectedTab=citation&volume=67

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