trichlorophosphate in 1,2-dichloro-ethane T=20°C; 15 h;

1: With tetrakis(triphenylphosphine) palladium(0) in dichloromethane T=20°C; Cycloaddition; 2: With toluene-4-sulfonic acid in dichloromethane; toluene T=20°C; protonolysis, lactonization; 48 h; Further stages.;

1.1: 91 percent / K2CO3 / acetone / 5 h / 20 °C 2.1: sulfur; morpholine; p-toluenesulfonic acid / 8 h / 120 - 130 °C 2.2: 66 percent / tetrabutylammonium bromide; NaOH / H2O / 8 h / 100 °C 3.1: 90 percent / POCl3 / 1,2-dichloro-ethane / 15 h / 20 °C View Scheme

1.1: sulfur; morpholine; p-toluenesulfonic acid / 8 h / 120 - 130 °C 1.2: 66 percent / tetrabutylammonium bromide; NaOH / H2O / 8 h / 100 °C 2.1: 90 percent / POCl3 / 1,2-dichloro-ethane / 15 h / 20 °C View Scheme

1: potassium hydroxide; sodium hydroxide / 210 °C 2: Erhitzen unter vermindertem Druck View Scheme

1: aq.-ethanolic KOH-solution 2: potassium hydroxide; sodium hydroxide / 210 °C 3: Erhitzen unter vermindertem Druck View Scheme

1: H2O2; aqueous NaOH 2: Erhitzen unter vermindertem Druck View Scheme