Stereoselective synthesis of stable isotope-labeled L-α-amino acids: Electrophilic amination of Oppolzer's acyl sultams in the synthesis of L-[15N]alanine, L-[15N]valine, L-[15N]leucine, L-[15N]phenylalanine and L-[1-13C, 15N]valine

Using 1-chloro-1-[15N]nitrosocyclohexane, we have prepared five L-[α-15N]amino acids. The stereoselective electophillic hydroxyamination of (S)-acylbornane-10,2-sultams, followed by ZnO/H+ reduction, and alkaline cleavage of the chiral auxiliary, gave the amino acids in 97.2–99.5% e.e. By starting with labeled (S)-acylbornane-10,2-sultams this stereoselective route could be to prepare many 13C and/or 15N isotopomers of α-amino acids.