${\left(\mathrm{R}\right)}_2 \mathrm{LiCu} \stackrel{\mathrm{R}\text{'}\mathrm{Br}}{\to } \mathrm{R}-\mathrm{R}\prime +\mathrm{R} -\mathrm{Cu}+\mathrm{LiBr}$

This is called Corey-House method of synthesizing alkanes. This, follow Mechanism.

.Alkyl halides react with lithium in dry ether to form alkyl lithium. This alkyllithium reacts with CuI to give Dialkyl Lithium Cuprate known as Gilman reagent. This dialkyl lithium cuprate reacts with alkyl halide to give alkane and the reaction is known as Corey-House synthesis