N-chloro-succinimide; dimethylsulfide in toluene T=-25°C; 2 h;

1: TsOH / ethyl acetate / 1.5 h / Ambient temperature 2: MCPBA, NaHCO3 / CH2Cl2 / 1 h / 0 °C 3: 93 percent / (i-PrO)3Al / toluene / 6 h / Heating View Scheme

1: TsOH / ethyl acetate / 1.5 h / Ambient temperature 2: MCPBA, NaHCO3 / CH2Cl2 / 1 h / 0 °C 3: 93 percent / (i-PrO)3Al / toluene / 6 h / Heating 4: 99 percent / propionic acid / 1 h / 140 °C 5: 94 percent / 2 N NaOH / methanol / 4 h / Ambient temperature View Scheme

1: 92 percent / N-chlorosuccinimide, Me2S / toluene / 2 h / -25 °C 2: 89 percent / TsOH / ethanol / 12 h / Heating View Scheme