1.1: N,N-dimethyl-aniline / Inert atmosphere 2.1: trichlorophosphate / 1,2-dichloro-ethane / 90 °C 3.1: N,N-dimethyl-formamide / 4 h / Reflux 4.1: hydrazine hydrate / tetrahydrofuran / 24 h / 20 °C 4.2: 0.5 h / pH 3 5.1: 24 h / Reflux View Scheme

1.1: N,N-dimethyl-formamide / 4 h / Reflux 2.1: hydrazine hydrate / tetrahydrofuran / 24 h / 20 °C 2.2: 0.5 h / pH 3 3.1: 24 h / Reflux View Scheme

1.1: hydrazine hydrate / tetrahydrofuran / 24 h / 20 °C 1.2: 0.5 h / pH 3 2.1: 24 h / Reflux View Scheme

1.1: trichlorophosphate / 1,2-dichloro-ethane / 90 °C 2.1: N,N-dimethyl-formamide / 4 h / Reflux 3.1: hydrazine hydrate / tetrahydrofuran / 24 h / 20 °C 3.2: 0.5 h / pH 3 4.1: 24 h / Reflux View Scheme

1.1: sulfuric acid; nitric acid / 1 h / Heating 2.1: N,N-dimethyl-aniline / Inert atmosphere 3.1: trichlorophosphate / 1,2-dichloro-ethane / 90 °C 4.1: N,N-dimethyl-formamide / 4 h / Reflux 5.1: hydrazine hydrate / tetrahydrofuran / 24 h / 20 °C 5.2: 0.5 h / pH 3 6.1: 24 h / Reflux View Scheme

24 h; Reflux;