[Mager]

I am curious to know when one would want to use a Heck Rxn. Vs. a Suzuki Rxn. Vs. using a Gilman reagent?

From my understanding a Heck Rxn is used when wanting to link two sp2 carbons. Same for a Suzuki Rxn.  A Gilman reagent can add an alkyl group to an aryl, vinyllic or alkyl halide ( if I'm correct ).

My confusion is understanding what the differences in these reactions is and when you would want to apply one vs another in a given circumstance?

[kriggy]

Well, you need to compare them in a way that makes sence ie. if you want to make a same compound. If that is the case (as in hypothetical example shown bellow) then in my opinion:

a) do I have the right starting materail? In the example it seems obvious to use heck because the boronic acid or halide might not be available/easy to handle or are just expensive (this Includes catalysts needed for Heck and Suzuki as well)

b) If one does not work or give poor yields compared to others. The heck reaction might not work in this case for some reason but the suzuki might so it might be better even if the boronic acid might be difficult to get etc..

It realy gets down to the specific cases and cant realy be generalized

[Mager]

Thank you Kriggy.  That gives me a fair understanding.  It makes sense that in real application it would be dependent on particular circumstances.  I appreciate your response.