The invention relates to a process for the preparation of the compound of formula (I), which process comprises a) reacting a compound of formula (II), wherein X is chloro or bromo, with an organometallic species in an inert atmosphere to a halobenzyne of formula (X), reacting the halobenzyne of formula X so formed with cyclopentadiene to (III), b) reacting III in the presence of an inert solvent with an oxidant to (IV), c) reacting IV in the presence of a Lewis acid and a hydride source to (V), d) reacting V in the presence of an oxidizing agent, a base and an inert solvent to (VI), e) converting VI in the presence of a phosphane and CCl4 or CHCl3 to (VII), and either f1) reacting VII with NH3 in the presence of a catalyst to the compound of formula (VIII); and g) reacting VIII in the presence of a base with a compound of formula (IX), to the compound of formula (I); or f2) reacting the compound of formula (VII), in the presence of a solvent, a base, a copper catalyst and at least one ligand with the compound of formula (IXa), to the compound of formula (I).