water; hydrophobic polystyrene-supported sulfonic acid 36 h; Heating;

1,4-dibromo-butane; potassium carbonate; sodium iodide; trans-di(μ-acetato)bis[o-(di-o-tolylphosphino)benzyl]dipalladium(II) in N,N-dimethyl-formamide T=90°C; cross-coupling; 18 h;

(i) Raney-Ni, THF, (ii) Raney-Ni, (iii) KOH, aq. EtOH; Multistep reaction;