27/-Pyrimido triazines

Pyrimido[5,4-e][l,2,4]triazine-5,7-dione, N-methyl-applications, 3, 456 Pyrimido-1,2,4-triazinediones synthesis, 2, 78 Pyrimidotriazines synthesis, S, 338... 

Pyrimido[5, 4 4,5]pyrazolo[3,2-c][l,2,4]triazine derivatives 1049and 1050 were prepared by treatment of diazo compound 1048, prepared from 1047, with pentane-2,4-dione and ethyl acetoacetate, respectively [92JCS(Pl)239]. 

Several new 2,4-disubstituted pyrrolo[2,l- [l,2,4]triazines, which can be further elaborated, and pyrrolo[5,1 -c]pyrimido[4,5-e] [ 1,2,4]triazines have been made by the reaction of iV,Af-dimethyl-dichloromethyleniminium chloride with l-aminopyrrole-2-carbonitrile and ethyl 4-aniino-3-cyanopyrazolo 5,l-c][l,2,4]triazine-8-carboxylate respectively (Scheme 7) <9613037 >. 

Refluxing of hydrazine 60 in acetic acid in the presence of sodium acetate resulted in the formation of 6-methyl-3-oxo-8-phenyl-3,4-dihydro-2/7-pyrimido[6,l-r-][l,2,4]triazine-9-carbonitrile 61 in good yield <1997IJB269> (Equation 2). 

The relevant heterocycles that belong to this type of ring system are the pyrimido[jc,y-z][l, 2,4]triazines and the [ 1,2,4]triazino[x,y-z]quinazolines. 

Diamino-4(3/f)pyrimidinones on reaction with a-diketones give (84JHC1537 85JHC1317) pyrimido[l,2- ][l,2,4]triazines 240. Similarly, the condensation of 2,3-diamino-4(3i/)pyrimidinones with cyclohexandi-one, 1,2-naphthoquinone, acenaphthenequinone, and phenanthraquinone gives the respective condensed pyrimidotriazines of general structure 241 (85JHC1317). 

The [l,2,4]triazolo[4, 3 3,4]pyrimido[2,l-c][l,2,4]triazines 253 were prepared (75G1029) by cyclization of hydrazine 251 with phenacyl bromides, which took place via 252. 

Thermal cyclization of 254 afforded 255, which reacted with hydrazine to give 256. Heating a suspension of 256 in DMF gave 6,10-dihydro-6//-pyrido[3, 2 5,6]pyrimido[2,1 -c] [ 1,2,4]triazin-5-one 259 via the intermediates 257 and 258 (86JHC509). 

Pyrido[3,2-c]pyrimido[2, l-c][ 1,2,4] triazine derivatives were prepared, and the diuretic, natriuretic, and kaliuretic activities determined (90AF1349). 

Cyclizations of 6-(l-alkylhydrazino)isocytosine 260 with the appropriate a-haloketones or ethyl bromopyruvate under acidic conditions gave (80JOC3919) exclusively the 6-amino-l,4-dihydro-8H-pyrimido[6,l-c]-[l, 2,4]triazin-8-ones 261. 

Treatment of 3-methyl-6-(l-methylhydrazino)uracil 262 with phenacyl bromides in ethanol afforded (78H1571 81CPB379) the pyrimido-[4,3-c][l,2,4]triazines 264 in addition to 263. 

This ring system is also present in the tricyclic heterocycles isoxazolo-[5, 4 4,5]pyrimido[6, l-c][l, 2,4]triazines. They were prepared (88JIC500)... 

Derivatives of the pyrimido[4,5-e][l,2,4]triazines at the 7-position were prepared (75JOC2329) by displacement of the respective chloro derivatives. Reaction of pyrimidotriazines 291 or 294 (R = S02Me) with acetylenic alcohols or amines gave azalumazines 292 or azapterins 295, respectively, with dienophilic side chains (88JOC800). Compounds 292 or 295 underwent intramolecular Diels-Alder reaction to give 6,7-annulated 5-deazapteridines 293 and 296, respectively (88JOC3568). 

Benzopyrano[4,3-e]pyrimido[l,2-6][l,2,4]triazines 759 and benzopy-rano[3,4-e]pyrimido[l,2-6][l,2,4]triazines 762 were prepared by reaction of the aminobenzopyranotriazines 758 or 761 with /3-keto esters. Catalytic reduction of 759 and 762 afforded the tetrahydro derivatives 760 and 763, respectively (90JHC1917). 

Cyclization of 776 with ortho-esters gave (83JOC1628) [l,2,4]triazolo-[4,3-fc]pyrimido[5,4-< ][ 1,2,4]triazines 777, whereas reaction with sodium nitrite afforded the corresponding tetrazolopyrimidotriazine 778.3-Azido-pyrimido[4,5-e][l, 2,4]triazine 779 exists in a cyclic form as tetrazolo derivative 780, as shown by X-ray analysis (86KGS114). In solution the position of the 779 780 equilibrium depended on temperature and solvent. Higher temperatures favored 779. Azido compound 779 predominated in water, and tetrazolo compound 780 predominated in pyridine. Addition of sodium azide to the aqueous solution shifted the equilibrium toward 780. The... 

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