[shrikantvarma]

is lithium dialkyl cuprate commercially available or we have to use it freshly prepared ??which one is good for reaction??

[Doc Oc]

You have to make it.  Your question is too non-descript to answer the rest.

[McCoy]

is lithium dialkyl cuprate commercially available or we have to use it freshly prepared ??which one is good for reaction??

The first bit has been answered by J - bone.
I'll guess what you meant in second the question.
lithium dialkyl cuprate is good for conjugate addition reaction while Grignard or alkyllithium is good for direct addition at carbonyl.

Cheers.