1: 94 percent Chromat. / tetrabutylammonium bromide / toluene / 3 h / 90 °C 2: 85 percent / 50percent aqueous NaOH, tetrabutylammonium hydrogen sulfate / benzene / 70 °C View Scheme

tetrabutylammomium bromide in toluene T=90°C; 3 h;

1: 94 percent Chromat. / tetrabutylammonium bromide / toluene / 3 h / 90 °C 2: 85 percent / 50percent aqueous NaOH, tetrabutylammonium hydrogen sulfate / benzene / 70 °C 3: 61 percent / pyridine; tetrahydrofuran / 2 h / Ambient temperature 4: 67 percent / KBr, tetrabutylammonium hydrogen sulfate / H2O; toluene / 2 h / 100 °C View Scheme