Preparation of labelled 2‐methoxy‐3‐alkylpyrazines: synthesis and characterization of deuterated 2‐methoxy‐3‐isopropylyrazine and 2‐methoxy‐3‐isobutylpyrazine

Efficient synthetic routes for a number of deuterated analogues of 2‐methoxy‐3‐isopropylpyrazines and 2‐methoxy‐3‐isobutylpyrazines have been developed involving the condensation of glyoxal with an α‐amino acid amide followed by methylation with iodomethane. In this way ²H₃]2‐methoxy‐3‐isopropylpyrazine, 2‐methoxy‐3‐isopropyl‐²H₂]pyrazine, ²H₃]2‐methoxy‐3‐isopropyl‐²H₂]pyrazine, ²H₃]2‐methoxy‐3‐isobutylpyrazine; 2‐methoxy‐3‐isobutyl‐²H₂]pyrazine and ²H₃]2‐methoxy‐3‐isobutyl‐²H₂]pyrazine were prepared and characterized by NMR and MS. Copyright © 2002 John Wiley & Sons, Ltd.