potassium fluoride; tetra-phenylphosphonium bromide in sulfolane; toluene T=210°C; P=300 Torr; Title compound not separated from byproducts;

1: 80 percent / phosphoryl chloride / acetonitrile; tetrahydrothiophene 1,1-dioxide; N,N-dimethyl-acetamide / 1 h / 70 °C 2: 90 percent / Ph4PBr, KF / tetrahydrothiophene 1,1-dioxide / 16 h / 130 - 140 °C 3: KF, PPh4Br / tetrahydrothiophene 1,1-dioxide; toluene / 210 °C / 300 Torr View Scheme

1: 100 percent / 1) 30percent fumic H2SO4 2) NaOH / 16 h / 110 - 115 °C 2: 80 percent / phosphoryl chloride / acetonitrile; tetrahydrothiophene 1,1-dioxide; N,N-dimethyl-acetamide / 1 h / 70 °C 3: 90 percent / Ph4PBr, KF / tetrahydrothiophene 1,1-dioxide / 16 h / 130 - 140 °C 4: KF, PPh4Br / tetrahydrothiophene 1,1-dioxide; toluene / 210 °C / 300 Torr View Scheme

1: 90 percent / Ph4PBr, KF / tetrahydrothiophene 1,1-dioxide / 16 h / 130 - 140 °C 2: KF, PPh4Br / tetrahydrothiophene 1,1-dioxide; toluene / 210 °C / 300 Torr View Scheme