The bond Li-C is the most labile among another bonds Li-X and so it is not likely to built it. If You try to react any Li compound (LiH for example) with any active reagent (BuX) You will obtain LiX and butane. ONLY if the reacnion will have no another choice it will go to Li-C bond creation. So if we have Li-Li (or may be Li-Na? bonds) this compons may be useful in obtaining BuLi. All Lithium sats are unuseful. We have at first obtain Li as metall (by electrilisys) and then involve it in reaction with BuCl to obtain BuLi
In what reaction? there are a lot of metal-organic compounds. In some cases it can be Gringard reagents (RMgX), in some cases another metals. But as a rule lithium organic compounds is the MOST active (Na- organic compounds of course are more active but VERY unstable) so in such reaction as LITHIATION of benezene (ArH to ArLi) all other metal-organic compouns are not effective