1: 81 percent / NaH / dimethylformamide / -50 °C 2: dimethyl(methylthio)sulfonium tetrafluoroborate, MS 4A / acetonitrile / -20 °C 3: 1 M NaOH / acetonitrile / 0 °C 4: Dowex 50 / ethanol; H2O View Scheme

1: 81 percent / NaH / dimethylformamide / -50 °C 2: dimethyl(methylthio)sulfonium tetrafluoroborate, MS 4A / acetonitrile / -20 °C 3: 1 M NaOH / acetonitrile / 0 °C 4: 93 percent / Dowex 50 / ethanol; H2O View Scheme

1: 83 percent / NaH / dimethylformamide / 0 °C 2: dimethyl(methylthio)sulfonium tetrafluoroborate, MS 4A / acetonitrile / -50 °C 3: 1 M NaOH / acetonitrile / 0 °C 4: 81 percent / Dowex 50 / ethanol; H2O View Scheme