[thenuttyprofessor]

My teacher talked about this in class but it's not in our book.  Wikipedia has the reaction as:

R-X + 2Li → R-Li + Li-X
2RLi + CuI → R2CuLi + LiI
R2CuLi + R'-X → R-R' + RCu + LiX

He gave an example of

                 diethyl                  CuI                Cu
CH3-I + Li ------------>CH3Li----------->(CH3)2     Li
                 ether

          Cu
(CH3)2    Li + CH3CH2CH2CH2CH2-I---> CH3CH2CH2CH2-C + CH3CU + LiI


I don't understand what the Cu over the Li means.  We are just beginning to learn orgnanic reactions and he did not explain this.  Also it seems like he took a shortcut or something.  This is the way I understand it should occur:

CH2-I + 2Li ---> CH3-Li + Li-I

2CH3Li + CuI ---> (CH3)2CuLi + LiI

(CH3)2CuLi + CH3CH2CH2CH2CH2-I ----> CH3-CH2-CH2-CH2-C  + CH3CU + LiI


is my equation saying the same thing?  i dont understand his shortcuts.  how does the pentyl iodide come out of nowhere?

it just doesn't make since to me.  please help me understand.  thank you.

[AWK]

look at more advanced reference, eg:
David S. Surry and David R. Spring
Chem. Soc. Rev., 2006, 35, 218–225

[se7en47]

2RLi + CuI → R2CuLi + LiI

for that part of the corey posner

how do you decide what lithium dialkylcuprate you should use?

[sjb]

Well, it depends what nucleophile you want to add, doesn't it? Or am I misunderstanding your question?

[Squirmy]

          Cu
(CH3)2    Li + CH3CH2CH2CH2CH2-I---> CH3CH2CH2CH2-C + CH3CU + LiI

You're missing some pieces in the bolded product.