Re: ORGLIST:how to suppress side reaction?

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From: David O'Dell (dko$##$ou.edu)
Date: Mon Mar 03 2003 - 11:08:29 EST

Peter,

If you want to make nitrobiphenyl, try starting from the aryl bromides and
iodides, they are more reactive than chlorides in Pd catalyzed cross
coupling reactions. I have seen papers dealing with the use of aryl
chlorides to make nitrobiphenyl, but they were employing the Suzuki
coupling with phenyl boronic acid. Check these references.

Molander, G. A.; Biolatto, B. Org. Lett. 2002, 4, 1867-1870.

Shimizu, K.; Kan-no, T.; Kodama, T.; Hagiwara, H.; Kitayama, Y. Tet.
Lett. 2002, 43, 5653-5655.

Feuerstein, M.; Doucet, H.; Santelli, M. Synlett 2001, 9, 1458-146

Wolfe, J. P.; Singer, R. A.; Yang, B. H.; Buchwald, S. L. J. Amer. Chem.
Soc. 1999, 121, 9550-9561.

Later

David

>How about using an excess of the starting material
>1-chloro-4-nitro-benzene? It's may be easier to separate the starting
>material from the reaction mixure.
>
>
>
>Y. Zhou
>
> >From: "peter walla"
> >To: everybody$##$orglist.net
> >Subject: ORGLIST:how to suppress side reaction?
> >Date: Thu, 27 Feb 2003 18:59:42 +0100 (CET)
> >
> >Hi Dear Everybody!
> >Please, could you someone tell me, how to supress the side reaction-
> formation of biphenyl (from phenylzinkiumchloride), when the reactant is
> 1-chloro-4-nitro-benzene and phenylzinkiumchloride (prepared from
> phenylmagnesiumchloride and zinc chloride) under 5 mol% Pd(PPh3)4 as
> catalyst in refluxing THF for 2 hours. The products are 4-nitrobiphenyl
> and biphenyl, but i dont want to separate it by mean of chromatography,
> because of similar Rf factors. Would addition of LiCl into the reaction
> mixture help to supress formation of biphenyl? Or what should I add
> there? I want to do just with palladium catalyst, and not with nickel.
> Or, please, how should I find this information in web, or scifinder or
> beilstein commander?
> >I appreciate any advice, ít is very important to me.
> >Thank you!
> >Peter
> >
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