Synthesis of Azido-Containing Amino Acids

Sodium bromide (NaBr), sodium sulfide nonahydrate (Na₂S•9H₂O), sodium cyanide (NaCN), sodium nitrite (NaNO₂), sodium methyl thiolate (NaSCH₃), sodium thiocyanate (NaSCN), sodium fluoride (NaF), L-glycine, and ammonium formate (NH₄HCO₂) were purchased from Sigma-Aldrich (St. Louis, MO). Sodium azide (NaN₃) was purchased from EMD Chemicals, Inc. (Gibbstown, NJ). Potassium cyanate (KOCN) was purchased from Alfa Aesar (Ward Hill, MA). Sodium nitrate (NaNO₃) was purchased from J. T. Baker (Phillipsburg NJ). (2S)-2-Amino-4-azido-butanoic acid (4-N₃-Aba) was obtained from Toronto Research Chemicals Product List (North York, Canada). All other chemicals (except for 4-NO₂-Aba, which was synthesized as summarized below) were obtained from sources previously noted.^{16 (link),24 (link)} Purchased reagents were used as received, without purification.