Abstract4‐15N‐2,3,5‐Trimethylpyrazine (1) was synthesized by dechlorination of 4‐15N‐6‐chloro‐2, 3, 5‐trimethylpyrazine (5) the key intermediate, derived from15N‐DL‐alanine (3).1‐15N‐2,3,5‐Trimethylpyrazine (2) was prepared by decarboxylation of 1‐15N‐2, 3, 5‐trimethyl‐pyrazine‐6‐carboxylic acid (10) obtained by the Pummerer type rearrangement of 1‐15N‐tetramethylpyrazine 1‐oxide (1) followed by oxidation.1‐ And 4‐oxides and 1,4‐dioxides of the above15Ntrimethylpyrazines were also obtained by treatment with sodium perborate in acetic acid.15N NMR spectra of the compounds thus prepared were measured an