1: With methanesulfonyl chloride; triethylamine in dichloromethane T=0°C; 2 h; Inert atmosphere; 2: With methanol in dichloromethane T=20°C; 0.5 h; Inert atmosphere; 3: With triethylamine in dichloromethane T=55°C; 12 h; Inert atmosphere;

1.1: N-ethyl-N,N-diisopropylamine / 48 h / 135 °C / Inert atmosphere 2.1: methanesulfonyl chloride; triethylamine / dichloromethane / 2 h / 0 °C / Inert atmosphere 2.2: 0.5 h / 20 °C / Inert atmosphere 2.3: 12 h / 55 °C / Inert atmosphere View Scheme