chloro-trimethyl-silane; cyclohexa-1,4-diene in chlorobenzene T=170°C; Bergman cyclization;

cyclohexa-1,4-diene in chlorobenzene T=150°C; Bergman cyclization; 5 h;

potassium carbonate in methanol T=20°C; 3 h;

1: tetrabutylammonium iodide / Pd(PPh3)2Cl2; CuI / triethylamine; dimethylformamide / 8 h / 70 °C 2: K2CO3 / methanol / 3 h / 20 °C View Scheme

1: 100 percent / aqueous K3PO4 / toluene / 3 h / 20 °C 2: tetrabutylammonium iodide / Pd(PPh3)2Cl2; CuI / triethylamine; dimethylformamide / 8 h / 70 °C 3: K2CO3 / methanol / 3 h / 20 °C View Scheme