SYNTHESIS AND N-15 NMR-SPECTRA OF 1-N-15-2,3,5-TRIMETHYLPYRAZINE AND 4-N-15-2,3,5-TRIMETHYLPYRAZINE AND THEIR N-OXIDES

4-N-15-2,3,5-Trimethylpyrazine (1) was synthesized by dechlorination o f 4-N-15-6-chloro-2,3,5-trimethylpyrazine (5), the key intermediate, d erived from N-15-DL-alanine (3). 1-N-15-2,3,5-Trimethylpyrazine (2) wa s prepared by decarboxylation of 1-N-15-2,3,5-trimethyl-pyrazine-6-car boxylic acid (10) obtained by the Pummerer type rearrangement of 1-N-1 5-tetramethylpyrazine 1-oxide (1) followed by oxidation. 1- And 4-oxid es and 1,4-dioxides of the above N-15-trimethylpyrazines were also obt ained by treatment with sodium perborate in acetic acid. N-15 NMR spec tra of the compounds thus prepared were measured and the assignment of two N-15 signals were certified.