1: 98 percent / 1.) NaH; 2.) tetrabutylammonium iodide / tetrahydrofuran / 2 h / Ambient temperature 2: 87 percent Spectr. / POCl3 / pyridine; CH2Cl2 / 48 h / -30 °C 3: 93 percent / sodium / diethyl ether; liquid ammonia / 0.67 h / -40 °C 4: 90 percent / pyridinium chlorochromate / CH2Cl2 / 1.25 h / Ambient temperature View Scheme

hydrogenchloride in water; toluene

n-butyllithium; p-toluenesulfonyl chloride in tetrahydrofuran; hexane T=0 - 20°C;

carbon dioxide in water T=140°C; P=3900.39 Torr; 2 h; stereoselective reaction;

potassium tert-butylate; carbonic acid dimethyl ester T=90°C; 6 h; Product distribution / selectivity;

toluene-4-sulfonic acid in dichloromethane 0.5 h; Heating; Title compound not separated from byproducts;

toluene-4-sulfonic acid in dichloromethane 30 h; Heating; Title compound not separated from byproducts;