1.1: 100 percent / Amberlyst H-15 / tetrahydrofuran / 48 h / 20 °C 2.1: BH3*THF / tetrahydrofuran / 24 h / 65 °C 2.2: aq. HCl / tetrahydrofuran / 1 h / 20 °C 2.3: 84 percent / Et2NH / tetrahydrofuran / 16 h / 20 °C 3.1: 82 percent / 24 h / 120 °C 4.1: 86 percent / polymer-supported chromic acid / tetrahydrofuran / 48 h / Heating View Scheme

1.1: SOCl2 / tetrahydrofuran 2.1: sodium hydride / dimethylformamide / 0.33 h / 0 °C 2.2: 59 percent / dimethylformamide / 18 h / 20 °C 3.1: 78 percent / LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C 4.1: 87 percent / CBr4; Ph3P / tetrahydrofuran / 3 h / 20 °C 5.1: tetrahydrofuran View Scheme

thionyl chloride in dichloromethane; N,N-dimethyl-formamide T=0°C; 0.75 h; Inert atmosphere;