masterbomb - 8-5-2007 at 09:52
First of all: Hello and sorry for my bad english(I'm just a pupil) 
I'm from Germany and I have a question 
Is it possible to couple Phenyllithium with anthracene derivates like 9,10 - dibromoanthracene or 9-chloroanthracene without any catalalyst like
PdCl2(dpp) or Palladiumtetrabistriphenylphosphin; Nickel etc... I would like to work in Anisole so that i'm able to work at a higher temperature.. If
it doesn't work; would it help to add some CuI or a high base like K(t-BuO) to produce temporary other metallRs which are more reactiv?
JohnWW - 8-5-2007 at 17:56
Phenyllithium is LiC6H5, containing the C6H5- anion; so, in theory, it could be made to couple with anthracene, or halogenated anthracenes, or similar
compounds, in a suitable aprotic polar solvent, either through the heat-of-formation of LiBr or LiCl as the driving-force, or through a small degree
of ionization of the anthracene derivative giving a carbocation intermediate and Cl- or Br-. However, steric hindrance of the incoming C6H5 group
would have to be minimal. With some anthracene derivatives or similar polycyclic aromatic compounds, the positive charge on the carbocation
intermediate may be delocalized by resonance, which would favor the reaction but may result in two or more isomeric products.
Sandmeyer - 31-5-2007 at 05:41
Unless there is a ref example you must preform the experiment to answer your own question. I doubt the direct substitution will work. And even if you
used Pd(0) ligand, you first need to make the boronic acid, you can't use PhLi directly. If you want to keep things a bit more simple, try first
Ullmann biaryl synthesis, there have been recent examples in the litt. on the prep. of assymetric biaryls (esp when one ArX is electon rich and other
electrondeficient, which seems to avoid homocpupling). Another option is Kumada coupling, where phenylmagneziumbromide cuples either directly with
Ar-X with Ni(II) catalysis, or where PhMgBr is transmetallated in situ with ZnCl2, then coupled with ArX with either Pd(0) or Ni(II) catalysts... Best
is to go to the library for this stuff and spend some time..
EDIT: Get some papers from Paul Knochel, he is obsessed with this stuff and has published a lot on this topic...
[Edited on 31-5-2007 by Sandmeyer]