palladium diacetate; 3,4,7,8-tetra-methyl-1,10-phenanthroline; 2,4,6-trimethyl benzoic acid in toluene T=140°C; P=30400 Torr;

1.1: toluene-4-sulfonic acid; hydroquinone / benzene / Reflux; Azeotropic water removal 2.1: dimethylsulfide borane complex / tetrahydrofuran / 2 h / 0 - 20 °C / Inert atmosphere 2.2: 1 h / 20 - 40 °C 2.3: 20 - 30 °C View Scheme

toluene-4-sulfonic acid; hydroquinone in benzene RefluxAzeotropic water removal;