Dimethyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate (1) reacts with isocyanates to afford the 2,7-disubstituted 1H,6H-diimidazo[1,5-b:1',5'-e][1,2,4,5]tetrazine-1,3,6,8(2H,7H)-tetron es 2a-m, a hitherto unknown ring system. The linear annulation of 2m was established by X-ray analysis, and as a consequence the 1,4-dihydro tautomer found to be the main constituent of all other potential isomers. Compound 1 reacts with isothiocyanates to give the corresponding 1,6-dithioxo derivatives 5a,b as well as the 7-substituted methyl 2,6,7,8-tetrahydro-8-oxo-6-thioxoimidazo[1,5-b][1,2,4, 5]tetrazine-3-carboxylates 6b,c respectively, while the unsymmetrically substituted 2-tert-butyl-7-(4-chlorophenyl)-6-thioxo-1H,6H-diimidazo[1,5-b:1',5'-e ][1,2,4,5]tetrazine-1,2,8-(2H,7H)-trione (8) is obtained from 6c and the corresponding isocyanate.
ASJC Scopus subject areas
- Organic Chemistry