ub.4 ' is hydrogen or a halogen atom, especially chlorine, bromine or iodine, reacting a compound of the formulaVIIIb in which Y.sub.4 ' is hydrogen with an organometallic compound, for example a metal derivative of an aliphatic hydrocarbon, for example with butyllithium, or reacting a compound of the formula VIIIb in which Y.sub.4 ' is a halogen atom with a metalof the formula M.sup.II.The amino-