1: 81 percent / NaH; p-toluenesulfonyl chloride / tetrahydrofuran / 0.5 h / 20 °C 2: 98 percent / AcOH; AcONa / H2O / -5 - 5 °C / pH 4 3: 82 percent / H-mordenite; AcOH / 5 h / Heating View Scheme

triphenylphosphine; diethylazodicarboxylate in tetrahydrofuran T=20°C; 3 h;