1: With toluene-4-sulfonic acid in methanol T=0 - 5°C; 0.5 h; 2: With N-bromosuccinmide in methanol T=0 - 5°C; 6 h;

aluminium trichloride in 1,2-dichloro-ethane 1 h; below 5 deg C;

1.1: AlCl3, aluminium chloride / dichloromethane / 0.5 h / 0 - 5 °C / |Inert atmosphere 1.2: 0.5 h / 0 - 5 °C / |Inert atmosphere 2.1: toluene-4-sulfonic acid / methanol / 0.5 h / 0 - 5 °C 2.2: 6 h / 0 - 5 °C View Scheme

1.1: sodium tetrahydroborate / tetrahydrofuran / 1 h / 5 - 10 °C / |Inert atmosphere 1.2: 4 h / 45 - 50 °C / |Inert atmosphere 2.1: potassium carbonate / water / 0.5 h / 25 - 30 °C 2.2: 12 h / 25 - 75 °C 3.1: hydrogen bromide / water; acetone / 7 h / 0 - 20 °C View Scheme

1.1: sodium tetrahydroborate / tetrahydrofuran / 1 h / 5 - 10 °C / |Inert atmosphere 1.2: 4 h / 45 - 50 °C / |Inert atmosphere 2.1: potassium carbonate / water / 0.5 h / 25 - 30 °C 2.2: 12 h / 25 - 75 °C View Scheme

1: With sodium tetrahydroborate in tetrahydrofuran T=5 - 10°C; 1 h; Inert atmosphere; 2: With AlCl3, aluminium chloride in tetrahydrofuran T=45 - 50°C; 4 h; Inert atmosphere;