4-toluenesulfonyl azide; triethylamine in acetonitrile T=20°C; 6 h;

1.1: n-butyllithium / tetrahydrofuran; hexane / 0.25 h / 0 °C 1.2: 95 percent / tetrahydrofuran; hexane / 0.5 h / cooling 2.1: 81 percent / triethylamine; p-toluenesulfonyl azide / acetonitrile / 6 h / 20 °C View Scheme