titanium tetrachloride in dichloromethane T=0 - 20°C;

1: 1-(2-chloroethoxy)-2,6-dibromo-4-fluorophenol With n-butyllithium in tetrahydrofuran T=-40°C; Metallation; 2: N,N-dimethyl-formamide in tetrahydrofuran T=-40 - 20°C; Formylation; Parham cyclization;

1: 85 percent / H2; AcOH / Pd/C / 12 h / 2585.74 Torr 2: 39 percent / TiCl4 / CH2Cl2 / 0 - 20 °C View Scheme

1.1: NaH / dimethylformamide / 0 °C 1.2: 80 percent / dimethylformamide / 18 h / 160 - 170 °C 2.1: 45 percent / polyphosphoric acid / benzene / 2.5 h / Heating 3.1: 85 percent / H2; AcOH / Pd/C / 12 h / 2585.74 Torr 4.1: 39 percent / TiCl4 / CH2Cl2 / 0 - 20 °C View Scheme

1: 45 percent / polyphosphoric acid / benzene / 2.5 h / Heating 2: 85 percent / H2; AcOH / Pd/C / 12 h / 2585.74 Torr 3: 39 percent / TiCl4 / CH2Cl2 / 0 - 20 °C View Scheme

1.1: K2CO3 / dimethylformamide 2.1: n-BiLu / tetrahydrofuran / -40 °C 2.2: 42 percent / tetrahydrofuran / -40 - 20 °C View Scheme

1: With bis (3-tert-butyl-4-hydroxy-5-methyl phenyl)-sulfide; 3-chloro-benzenecarboperoxoic acid in dichloromethane Bayer-Villiger reaction; 16 h; Heating; 2: With sodium hydroxide in ethanol T=20°C; 3 h;