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Topic: formylation  (Read 5493 times)

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Offline frenchy

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formylation
« on: March 10, 2009, 02:07:42 PM »
Hi,

Does anyone know a formylation technique on the 2 position of pyrrole that wouldn't involve DMF. My product doesn't crash out of reaction when I basify my Vilsmeyer Hack. My product is also fairly happy in water, meaning every time I wash my DCM layer I loose a lot of my product.

Cheers
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Offline sjb

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Re: formylation
« Reply #1 on: March 10, 2009, 04:37:31 PM »
What else is there on the ring? Could you e.g. methylate (or similar) then oxidize? Or perhaps Riemer-Tiemann (OH- / chloroform?)

S
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Offline frenchy

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Re: formylation
« Reply #2 on: March 10, 2009, 05:55:41 PM »
there is "just" an alkyl group on the 5 position.
Is Riemer-Tiemann not starting with an alcohol?
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Offline sjb

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Re: formylation
« Reply #3 on: March 11, 2009, 05:17:31 AM »
Hmm, sticking a methyl group on and oxidizing is not that useful then.

Could you vinylate and Wittig or similar?

Gatterman-Koch (though I'm not sure if the nitrogen on the pyrrole will affect things?)

I'm sure I've seen Riemer-Tiemanns without phenols, but can't find references at the moment, may be getting confused.
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Offline sjb

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Re: formylation
« Reply #4 on: March 11, 2009, 04:47:35 PM »
Quote from: sjb on March 11, 2009, 05:17:31 AM
Could you vinylate and Wittig or similar?

Erm, scrub that, Wittig of course goes the other way ;) (aldehyde to vinyl)
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Offline Dynamic

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Re: formylation
« Reply #5 on: March 12, 2009, 12:41:11 AM »
The Riemer Tiemanns conditions are reported to work on pyrrole.
http://www.freepatentsonline.com/4755613.html
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Offline frenchy

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Re: formylation
« Reply #6 on: March 12, 2009, 12:22:51 PM »
I've found the reference
http://pubs.acs.org/doi/pdf/10.1021/jo00206a012

Apparently it gives a fairly low yield but I guess it's always worth a shot
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Offline Dynamic

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Re: formylation
« Reply #7 on: March 15, 2009, 10:03:36 AM »
The yields were reported to be somewhat higher (95%) when solid KOH was used with a limited amount of water.
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