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The Heck reaction allows the synthesis of monomers in a one-step reaction. Catalyzed by Pd, bromoarenes are reacted with ethylene to form substituted styrenes and symmetrical stilbenes. Unsymmetrical stilbenes are obtained from substituted bromoarenes and styrenes. Substituted hydroquinones and terephthalic acids are also available in high yields. Poly(l,4-phenylenevinylene) is obtained starting from 4-bromostyrene. Experimental partA typical procedure for the synthesis of a styrene and a stilbene derivative is given. Experimental conditions for other monomers are shown in Tab. 1.Reagents: DMF: distilled over 4,4 '-methylenedi(pheny1 isocyanate) and dibutyltin dilaurate as catalyst. Pd(OAc)2: used as received (Degussa). Tri-o-tolylphosphine: synthesized according to lit. '). Triethylamine, tributylamine: distilled over KOH. Styrene: used as received (stabilized with catechol). 4-Vinylbenzamide (6):A flame-dried pressure vessel of 100 ml volume was loaded under argon with 7 g (35 mmol) of p-bromobenzamide, 0,21 g (0,7 mmol) of tri-o-tolylphosphine, 0,078 g (0,35 mmol) of palladium acetate, 5,46 ml (40 mmol) of triethylamine, and a teflon@coated stir bar. 60 ml of DMF were added and a pressure of 72 bar ethylene (room temperature) applied. The autoclave was heated to 130°C for 24 h. The reaction mixture was precipitated with 400 ml of water and the solid dissolved in acetone. The filtered solution was concentrated and the residue was purified by sublimation. Yield: 3,7 g (72%), m.p. 176-177 "C, determined by DSC (lit.5): 170°C).

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