Synthesis, structure analysis, and antitumor activity of 3,6-disubstituted-1,4-dihydro-1,2,4,5-tetrazine derivatives

Fourteen compounds of 3,6-disubstituted-1,4-dihydro-1,2,4,5-tetrazine derivatives were prepared and their structures were confirmed by single-crystal X-ray diffraction and the semi-empirical calculation of PM3 method. This reaction yields the 1,4-dihydro derivatives rather than the 1,2-dihydro derivatives. The central six-membered ring of 1,4-dihydro-1,2,4,5-tetrazine has a chair conformation and therefore is not homoaromatic. Their antitumor activities were evaluated in vitro by SRB method for A-549 and BEL-7402 cells, and MTT method for P-388 and HL-60 cells. The results show that there is one compound which is highly effective against P-388 cells and one compound which is highly effective against HL-60 cells. So it is a kind of compound which possesses potential antitumor activities and is worth to research further.