1: dimethylformamide / Ambient temperature 2: Cs2CO3 / dimethylformamide / 60 °C 3: 15percent aq. H2SO4, SiO2 / CH2Cl2 4: TFA / 1 h / Ambient temperature 5: benzene / 1 h / Heating View Scheme

1: dimethylformamide / Ambient temperature 2: Cs2CO3 / dimethylformamide / 60 °C 3: 15percent aq. H2SO4, SiO2 / CH2Cl2 4: TFA / 1 h / Ambient temperature 5: benzene / 1 h / Heating View Scheme

With  chloro-trimethyl-silane; lithium bromide in  acetonitrile 0.583333 h;