1: 83 percent / tetrahydrofuran; diethyl ether / 3 h / -78 °C 2: NCS, AgNO3 / H2O; acetonitrile 3: I2, KOH / 43 °C 4: KOH / methanol; H2O View Scheme

1: 73 percent / tetrahydrofuran; diethyl ether / 3 h / -78 °C 2: 1.) NCS, AgNO3; 2.) NaBH4 / 1.) CH3CN, 5 min; 2.) 1 h View Scheme

1: 73 percent / tetrahydrofuran; diethyl ether / 3 h / -78 °C 2: 73 percent / NCS, AgNO3 / H2O; acetonitrile 3: I2, KOH / 43 °C 4: KOH / methanol; H2O View Scheme