Disclosed is a kit for use in the production of a molecular probe for PET drug screening for the purpose of producing a compound containing a short-lived radionuclide for PET applications. Specifically disclosed is a kit comprising a compound represented by the formula (I), (II) or (III) or a salt thereof. In the formulae, X 1 , X 2 , X 3 , X 4 , X 5 and X 6 are as defined in the description.