Syntheses and Reactions of Some 2, 5-Disubstituted Pyrazine Monoxides

The reactions of 2, 5-dimethylpyrazine 1-oxide (XI), 2, 5-diethylpyrazine 1-oxide (XIII), 2-methyl-5-phenylpyrazine 1-oxide (XV), and 2-methyl-5-phenylpyrazine 4-oxide (XVI) with phosphoryl chloride or acetic anhydride were studied. 2, 5-Dichloro-3, 6-dimethylpyrazine (III) and 2, 5-dichloro-3, 6-diethylpyrazine (VII) were converted to the diketopiperazines, alanine anhydride (I) and α-aminobutyric anhydride (V), respectively, which were shown to exist in a cis configuration by examination of their PMR spectra.