[nameless]

If there is a meta directing substituent on a benzene ring i understand that friedel-craft reactions are not useful so an alkyl group cannot be added to benzene using this reaction. However, could a gilman reagent be used to alkylate the benzene. I am suppose to convert benzene to m-methylbenzonitrile. Can someone check to see if this reaction is possible?

[stewie griffin]

Essentially what you're proposing is an S_NAr reaction (nucleophilic aromatic substitution). Those types of reactions require an electron withdrawing group ortho or para to the leaving group. You don't have that, you're EWG is meta. Since we can't do a direct S_N2 on an aryl bromide, I don't think your proposal will work.
However, why not reverse the idea? Make the Gilman reagent from your starting aryl bromide. Use that then to attack methyl iodide.

[movies]

Isn't that the Corey–House reaction?

[stewie griffin]

Indeed it is the Corey-House reaction.   I think there would be no problem forming the aryl bromide derived lithium cuprate. But I just didn't think that you can use a gilman reagent to displace an aryl bromide...
Movies do you know if a Gilman reagent will displace an aryl bromide. Wiki seems to imply that it is possible.

[movies]

I don't really have any experience with it, but it looks like it should work.  The Corey–House doesn't rely on the electronic activation the way that S_NAr chemistry does.  It is more akin to a cross-coupling reaction.

[Schrödinger]

Do we know the mechanism of Corey-House synthesis? (not the one that wiki has to offer)

I heard from one of my friends that the mechanism is unknown...is it still unknown?

[movies]

Can you ever really know a mechanism?

Anyway, I would have expected a radical mechanism because the coupling occurs upon exposure to oxygen, but there is some evidence that suggests otherwise.  It seems that a more-or-less "usual" reductive elimination is the favored pathway.  There is a fairly recent review on some of this stuff: Chem. Soc. Rev., 2006, 35, 218–225.