1: 87 percent / NaH / tetrahydrofuran / 1) reflux, 4 h, 2) 130 deg C, 3 h, 0.1 Torr 2: 65 percent / diethyl ether / 17 h / 20 °C 3: 0.5 h / 120 - 130 °C View Scheme

sodium hydride in tetrahydrofuran 1) reflux, 4 h, 2) 130 deg C, 3 h, 0.1 Torr;

1: 87 percent / NaH / tetrahydrofuran / 1) reflux, 4 h, 2) 130 deg C, 3 h, 0.1 Torr 2: 65 percent / diethyl ether / 1 h / 20 °C 3: 65 percent / 2.5 h / 150 °C View Scheme

1: 87 percent / NaH / tetrahydrofuran / 1) reflux, 4 h, 2) 130 deg C, 3 h, 0.1 Torr 2: 32 percent / Tetrahydro-3,3,5,5-tetramethyl-4H-thiopyran-4-thion (8i) / diethyl ether / 1008 h / 20 °C View Scheme