An effective organic solvent system for the dissolution of amino acids

Dimethylformamide containing strong acids (CF3 COOH, HBF4. TosOH, etc.) and an excess of tertiary base with pK≤6 is an effective solvent system for the dissolution of amino acids and their derivatives. The preferable base is pyridine, which forms a system with an apparent pH of 5.3. Amino acids dissolved in this solvent system readily interact with acylating reagents (BOC2O, ZOSu, Fmoc‐OSu and activated derivatives of N‐protected amino acids). A number of BOC‐, Z‐, Fmoc‐amino acids, as well as several dipeptides, were synthesized using this solvent system with 80‐99%) yields. © Munksgaard 1996.