ORGLIST: RE: S-alkylation of 2-thiouracil

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From: by way of Joao Aires de Sousa (r.ragno$##$caspur.it)
Date: Wed Mar 19 1997 - 03:29:02 EST


On Tue, 18 Mar 1997, Eric Lucas wrote:

> Hi, Gianluca,
>
> Gee, that's a tough one! As I'm sure you know, cyclopropyl halides are
> generally very poor electrophiles because of the hybridization of the
> carbon. Have you thought about a Cu thiouracil reagent (sort of like a
> cuprate), reacted with cyclopropyl iodide? I know Cu-S bonds are
> awfully strong, but maybe it would work. (Or perhaps Ag). Cu reagents
> generally work by electron transfer (I believe), and the cyclopropyl
> iodide should react well with radicals.
>
> On the other hand, maybe it's easier to assemble the cyclopropane ring
> once it's already on the thiouracil. Perhaps, for example, you could
> make S-vinyl thiouracil, then cyclopropanate it with CH2N2/Pd catalyst,
> or with ICH2ZnI.
>
> Finally, could you use cyclopropane thiol as the nucleophile, and
> 2-iodouracil as the electrophile?
>
> These are just some random thoughts. Sorry that I can't offer a much
> better response.
>
> Good luck,
> Eric Lucas


Dear Eric,
Thank you for your answer. I'd already thought to a radical reaction but
I was afraid that the alkylation of the position 5 of the pyrimidine ring
(its behaviour is quite aromatic...) could also occur. Anyway, I'll
try...
Do you have any reference about the use of the catalysts you says?
Thank you again,

Gianluca "Blue Merlin" Sbardella

This was my original message. I apologise for any repetition...

> >
---------- > From: Gianluca Sbardella[SMTP:r.ragno$##$caspur.it]
> Sent: Tuesday, March 18, 1997 3:50 AM
> To: Multiple recipients of OrgChem; Multiple recipients of OrgList
> Subject: S-alkylation of 2-thiouracil
>
> Dear colleagues,
> I've synthesized many 6-substituted-2-alkylthio-4-oxo-pyrimidines by
> S-alkylation of 2-thiouracils with alkyl halides and potassium carbonate
> in DMF, but when I tried to introduce the cyclopropyl group in the same
> way (i.e. with cyclopropyl iodide) I failed. Do you have any suggestion?
> I'll summarize to the list the answers I'll get.
> Thank you in advance,
>
> Gianluca " Blue Merlin" Sbardella
>
> ***************************************************************
> * *
> * Dr. Gianluca Sbardella E-mail: r.ragno$##$caspur.it *
> * Dip. Studi Farmaceutici *
> * Universita' "La Sapienza" Phone: 39-6-49913814 *
> * P.le A. Moro, 5 Fax: 39-6-491491 *
> * 00185 Roma *
> * ITALY *
> * *
> * *
> * "Il destino e' quel che e', non c'e' scampo piu' per me.." *
> * (Gene Wilder, "Frankenstein Junior") *
> * *
> * "Destiny, destiny, no escaping that for me..." *
> * (Gene Wilder, "Young Frankenstein") *
> * *
> ***************************************************************
>
>
>
>
>

    ***************************************************************
    * *
    * Dr. Gianluca Sbardella E-mail: r.ragno$##$caspur.it *
    * Dip. Studi Farmaceutici *
    * Universita' "La Sapienza" Phone: 39-6-49913814 *
    * P.le A. Moro, 5 Fax: 39-6-491491 *
    * 00185 Roma *
    * ITALY *
    * *
    * *
    * "Il destino e' quel che e', non c'e' scampo piu' per me.." *
    * (Gene Wilder, "Frankenstein Junior") *
    * *
    * "Destiny, destiny, no escaping that for me..." *
    * (Gene Wilder, "Young Frankenstein") *
    * *
    ***************************************************************


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