1: toluene-4-sulfonic acid / benzene / 7 h / Reflux; Inert atmosphere 2: 20 palladium hydroxide on charcoal; hydrogen / ethanol; ethyl acetate / 2 h / 20 °C / Inert atmosphere 3: potassium carbonate / N,N-dimethyl-formamide / 5 h / 20 °C / Inert atmosphere View Scheme

1.1: toluene-4-sulfonic acid / benzene / 7 h / Reflux; Inert atmosphere 2.1: boron trichloride / dichloromethane; toluene / 12 h / -78 - 20 °C / Inert atmosphere 2.2: 0.5 h / 20 °C View Scheme