L-Alanine labelled with carbon-13 and nitrogen-15 has been prepared in
good yield and high optical purity from achiral precursors using alan
ine dehydrogenase This versatile approach may be simply adapted for th
e preparation of a range of isotopically labelled amino acids and effi
cient syntheses of [N-15]-labelled serine, valine, leucine and phenyla
lanine are described.