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

Using 1-chloro-1-[N-15]nitrosocyclohexane, we have prepared five L-[alpha-N-15]amino acids. The stereoselective electophillic hydroxyamination of (S)-acylbornane-10,2-sultams, followed by Zn-o/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 C-13 and/or N-15 isotopomers of alpha-amino acids.