1.1: pyridine; N,O-bis-(trimethylsilyl)-acetamide / 1 h / 20 °C / Inert atmosphere 1.2: 0.5 h / Inert atmosphere 1.3: Dowex 50WX2 (Na+ form) 2.1: CEM-SS culture medium / 37 °C / pH 7.4 / aq. buffer View Scheme