2,6-di-tert-butyl-4-methyl-phenol; tris-(o-tolyl)phosphine; lithium chloride; bis-triphenylphosphine-palladium(II) chloride; copper(I) bromide in N,N-dimethyl-formamide Heating;

1: 96 percent / aq. NaHSO3 / methanol; H2O / 24 h / Ambient temperature 2: diisopropylamine, butyllithium / tetrahydrofuran; hexamethylphosphoric acid triamide / - 20 deg C, 20 min; r.t., overnight 3: 30percent aq. oxalic acid / tetrahydrofuran / 1.5 h / Heating 4: Zn-Hg, HCl / toluene / 10 h / Heating 5: 47percent HBr / acetic acid / 10 h / 130 °C View Scheme