A large dissymmetric starphene molecule, the tetrabenzo[a,c,u,w]naphtho[2,3-l]nonaphene, can be obtained by first preparing a soluble precursor which is then sublimated on a Au(111) surface in ultra-high vacuum. In a second step, controlled annealings from 200°C to 275°C initiate two successive cyclodehydrogenation steps with the formation of 3 new carbon-carbon bonds. A second conformer is also stable enough during the annealing step to give another compound in similar yield, the benzodibenzo[7,8,9,10]naphthaceno[2,1-h]phenanthro[9,10p]hexaphene. The formation of this more hindered species stresses the importance of strong molecule-surface interactions during the cyclodehydrogenations steps of these large polyaromatic hydrocarbons.