Offer to buy a house available only cadastral number

We are offered to buy a house that stands on 17 acres of land, Kyiv region, at the moment only the cadastral number is available. Legally, a deal can take place, and what threatens the absence of state. property deed? What are the next actions? Buy and on your own behalf apply for privatization? Or still ask the seller to draw up to the end for himself and then sign the contract of sale. We are already faced with the 3rd proposal of this kind.