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 [ 2 H 3 ]2‐methoxy‐3‐isopropylpyrazine, 2‐methoxy‐3‐isopropyl‐[ 2 H 2 ]pyrazine, [ 2 H 3 ]2‐methoxy‐3‐isopropyl‐[ 2 H 2 ]pyrazine, [ 2 H 3 ]2‐methoxy‐3‐isobutylpyrazine; 2‐methoxy‐3‐isobutyl‐[ 2 H 2 ]pyrazine and [ 2 H 3 ]2‐methoxy‐3‐isobutyl‐[ 2 H 2 ]pyrazine were prepared and characterized by NMR and MS.