hydrogen; hexacarbonyl chromium in hexane T=175°C; P=38000 Torr; 3 h; Yield given;

1: 74 percent / triethylamine, 4-(N,N-dimethylamino)pyridine / CH2Cl2 / 2 h / 22 °C 2: 62.2 percent / tosyl azide, triethylamine / acetonitrile / 36 h / Ambient temperature 3: 45.5 percent / CuSO4, Cu(acac)2 / benzene / 24 h / Heating 4: 28.8 percent / 580 - 600 °C / 0.01 Torr 5: 60.5 percent / LiI / dimethylformamide / 2.5 h / Heating View Scheme

1: aq. HBr / 0 °C 2: (i) Mg, THF, (ii) /BRN= 1719743/ View Scheme

benzene

1: 84 percent / Et3N; DMAP / CH2Cl2 / 0.17 h / 0 °C 2: 2,6-di-tert-butyl-4-methylphenol / toluene / 6 h / 110 °C View Scheme

Yield given. Multistep reaction. Yields of byproduct given;