Synthesis of tritium labeled isotopomers of L ‐tyrosine

The synthesis of four selectively labeled isotopomers of L‐tyrosine, (L‐Tyr), using chemical and enzymatic methods is reported. Four tritium labeled isotopomers of L‐phenylalanine (L‐Phe) – [2‐3H]‐, [2′,6′‐3H2]‐, [3R‐3H]‐ and [3S‐3H]‐ have been synthesized using a combination of chemical and enzymatic methods. The labeled isotopomers of L‐Phe have been converted into [2 ‐3H]‐, [2′,6′‐3H2]‐, [3R‐3H]‐, and [3S‐3H]‐L‐Tyr by using the enzyme L‐phenyl‐alanine 4′‐monooxygenase.