Dihydro‐ und Tetrahydroderivate des 3,6‐Dimethyl‐1,2,4,5‐tetrazins

The scheme 1 shows those tetrahydro‐ and dihydroderivatives of the 3,6‐dimethyl‐1,2,4,5‐tetrazine (or s‐tetrazine), 8, which are theoretically possible without considering cis‐trans isomerism, together with the reaction pathways. We did not succeed in synthetizing the 3,6‐dihydroderivative, 7, and could not isolate the 1,2‐dihydrocompound, 4, the latter being probably easily convertible to the thermodynamically more stable 1,4‐dihydro‐s‐tetrazine, 5, via their common conjugate base 4,5B. The 1,4‐dihydro‐s‐tetrazine, 5, gives with 3,6‐dimethyl‐s‐tetrazine 8, a charge transfer complex, 15. The same compounds form in acidic or basic aquious solution stable radicals, 16B and 16S. The mode of formation of these radicals and the subsequent reactions are depicted in scheme 2.