sodium tetrahydroborate in ethanol T=-10°C; 24 h; Heating / reflux;

toluene-4-sulfonic acid in toluene Heating;

1: 1) NaH / 1) toluene, reflux, 30 min, 2) reflux, 1 h 2: 51.4 percent / NaBH4 / ethanol / 6 h 3: 94 percent / toluene-p-sulfonic acid / toluene / Heating View Scheme

1: 91 percent / diisobutylaluminium hydride / diethyl ether; hexane / 1) -40 deg C to room temperature, 2) room temperature, 12 h 2: 87 percent / N-bromosuccinimide, Me2S / CH2Cl2 / 5 h 3: 92 percent / m-chloroperbenzoic acid / CH2Cl2 / 12 h / 0 °C View Scheme

1: 91 percent / diisobutylaluminium hydride / diethyl ether; hexane / 1) -40 deg C to room temperature, 2) room temperature, 12 h 2: 87 percent / N-bromosuccinimide, Me2S / CH2Cl2 / 5 h View Scheme