1.1: sodium hydride / tetrahydrofuran; mineral oil / 0.5 h / 20 °C / |Inert atmosphere 1.2: 4 h / 20 °C 2.1: toluene-4-sulphonic acid monohydrate / ethanol / 16 h / |Inert atmosphere; |Reflux 3.1: potassium hydroxide / ethanol; water / |Reflux View Scheme

1: toluene-4-sulphonic acid monohydrate / ethanol / 16 h / |Inert atmosphere; |Reflux 2: potassium hydroxide / ethanol; water / |Reflux View Scheme

1.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 1 h / 20 °C 1.2: 4 h / 50 °C 2.1: potassium hydroxide / ethanol; water / |Reflux View Scheme