1: With chloroformic acid ethyl ester; triethylamine in acetone T=-20°C; Inert atmosphere; 2: With ammonia in water; acetone T=-20°C; 2 h; 3: With sodium hydroxide in water T=0°C;

1.1: chloroformic acid ethyl ester; triethylamine / acetone / -20 °C / Inert atmosphere 1.2: 2 h / -20 °C 1.3: 0 °C 2.1: acetone / water / 80 °C 3.1: ammonia / water / 5 h / 80 °C 3.2: 0 °C / pH 1 View Scheme

1.1: chloroformic acid ethyl ester; triethylamine / acetone / -20 °C / Inert atmosphere 1.2: 2 h / -20 °C 1.3: 0 °C 2.1: acetone / water / 80 °C 3.1: ammonia / water / 5 h / 80 °C 3.2: 0 °C / pH 1 4.1: potassium hydroxide / water / 30 h / 0 °C 4.2: 1.17 h / 0 - 80 °C 4.3: 0.5 h / 80 - 90 °C View Scheme

1.1: chloroformic acid ethyl ester; triethylamine / acetone / -20 °C / Inert atmosphere 1.2: 2 h / -20 °C 1.3: 0 °C 2.1: acetone / water / 80 °C 3.1: ammonia / water / 5 h / 80 °C 3.2: 0 °C / pH 1 4.1: potassium hydroxide / water / 30 h / 0 °C 4.2: 1.17 h / 0 - 80 °C 4.3: 0.5 h / 80 - 90 °C View Scheme

1.1: chloroformic acid ethyl ester; triethylamine / acetone / -20 °C / Inert atmosphere 1.2: 2 h / -20 °C 1.3: 0 °C 2.1: acetone / water / 80 °C 3.1: ammonia / water / 5 h / 80 °C 3.2: 0 °C / pH 1 4.1: potassium hydroxide / water / 30 h / 0 °C 4.2: 1.17 h / 0 - 80 °C 4.3: 0.5 h / 80 - 90 °C View Scheme