1: With water in tetrahydrofuran; methanol T=0°C; Inert atmosphere; 2: With potassium carbonate in tetrahydrofuran; methanol T=40°C; 5 h; Inert atmosphere; Further stages;

1.1: dichloromethane / 0.5 h / 0 °C 1.2: 0 - 20 °C 2.1: dichloromethane / 0.5 h / Molecular sieve 2.2: 0 °C 3.1: water / tetrahydrofuran; methanol / 0 °C / Inert atmosphere 3.2: 5 h / 40 °C / Inert atmosphere View Scheme

1.1: dichloromethane / 0.5 h / Molecular sieve 1.2: 0 °C 2.1: water / tetrahydrofuran; methanol / 0 °C / Inert atmosphere 2.2: 5 h / 40 °C / Inert atmosphere View Scheme