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Synthesis and reactivity of 3-tert-butyl-8-r-pyrimido-[4′,5′:3,4]pyrazolo[5,1-c][1,2,4]triazine-4,10(6h,9h)-dithiones

“…Some 1,2,4-triazines were found to exhibit pesticidal activity and various kinds of pharmacological activity [1,2]. We previously [3] synthesized 3-tert-butyl-8-R-pyrimido[4′,5′:3,4]pyrazolo [5,1-c]- [1,2,4]triazine-4,10(6H,9H)-diones 1 and 2 by reaction of 7-amino-3-tert-butyl-4-oxo-6H-pyrazolo[5,1-c]- [1,2,4]triazine-8-carboxamide with acylating agents.…”

“…By heating compound 1 with P 2 S 5 in boiling anhydrous pyridine we obtained 3-tert-butylpyrimido[4′,5′:3,4]-pyrazolo[5,1-c] [1,2,4]triazine-4,10(6H,9H)-dithione (3) (Scheme 1). In addition, 8% of 3-tert-butyl-4-thioxo-4,9-dihydropyrimido[4′,5′:3,4]pyrazolo[5,1-c]- [1,2,4]triazin-10(6H)-one (5) was isolated as by-product. Likewise, analogous treatment of compound 2 gave dithione 4, but no by-product like 5 was isolated (only its traces were detected).…”

“…The thioxo group in position 10 of compounds 3 and 4 was subjected to hydrazinolysis on heating with 85% hydrazine hydrate in alcohol. The C 4 =S group remained intact under these conditions, and the products were 3-tert-butyl-10-hydrazinyl-8-Rpyrimido[4′,5′:3,4]pyrazolo[5,1-c] [1,2,4]triazine-4(6H)-thiones 6 and 7. The mass spectrum of 6 displayed the molecular ion peak with m/z 291 [M + H] …”

“…Heating of compound 6 with excess formic acid resulted in formylation of the hydrazino group with formation of N′- (3-tert-butyl-4-thioxo-4,6-dihydropyrimido[4′,5′:3,4]pyrazolo [5,1-c] [1,2,4]triazin-10-yl)-formohydrazide (8); no subsequent intramolecular cyclization was observed. The carbonyl stretching vibration band appeared in the IR spectrum of 8 at 1679 cm -1 ; no such band was present in the spectrum of 6.…”

“…The reaction of 6 with sodium nitrite gave different products, depending on the conditions. By treatment of 6 with sodium nitrite in polyphosphoric acid at 0°C we obtained 3-tert-butyltetrazolo[1″,5″:3′,4′]pyrimido[5′,6′:3,4]pyrazolo-[5,1-c] [1,2,4]triazin-4(12H)-one (10); i.e., closure of tetrazole ring was accompanied by hydrolysis of the thioxo group. In the IR spectrum of 10, the carbonyl stretching vibration band was located at 1708 cm -1 (C 4 =O), and the mass spectrum contained the molecular ion peak with m/z 286 [M + H] + .…”