3‐Monosubstituted and 3,6‐Unsymmetrically disubstituted 1,2,4,5‐Tetrazines. A general method of synthesis

A stepwise procedure has been developed for the synthesis of 3,6‐unsymmetrically disubstituted‐ or 3‐monosubstituted‐1,2,4,5‐tetrazines, based upon the facile substitution either of an alkylthio group in 3,6‐bis(alkylthio)‐1,2,4,5‐tetrazines (1) and (2) by nitrogen nucleophiles, particularly by hydrazine, or of a bromo group, obtained by oxidation of a hydrazino group or by an independent synthesis, by carbon nucleophiles. The ultraviolet‐visible spectra and some nuclear magnetic resonance properties are discussed.