1.1: toluene / 18 h / 75 °C 2.1: thionyl chloride / toluene / 60 - 75 °C 3.1: 1-methyl-pyrrolidin-2-one / 0.67 h / 20 °C 3.2: 3 h / 40 °C 4.1: potassium carbonate; copper / N,N-dimethyl-formamide / 1 h / Reflux 5.1: sodium hydroxide / methanol / 6 h / Reflux View Scheme

1.1: thionyl chloride / toluene / 18 h / Reflux 2.1: toluene / 18 h / 75 °C 3.1: thionyl chloride / toluene / 60 - 75 °C 4.1: 1-methyl-pyrrolidin-2-one / 0.67 h / 20 °C 4.2: 3 h / 40 °C 5.1: potassium carbonate; copper / N,N-dimethyl-formamide / 1 h / Reflux 6.1: sodium hydroxide / methanol / 6 h / Reflux View Scheme

1.1: thionyl chloride / toluene / 60 - 75 °C 2.1: 1-methyl-pyrrolidin-2-one / 0.67 h / 20 °C 2.2: 3 h / 40 °C 3.1: potassium carbonate; copper / N,N-dimethyl-formamide / 1 h / Reflux 4.1: sodium hydroxide / methanol / 6 h / Reflux View Scheme

1: potassium carbonate; copper / N,N-dimethyl-formamide / 1 h / Reflux 2: sodium hydroxide / methanol / 6 h / Reflux View Scheme