2,4,6,-triaminopyrimidine

Interest continues in the preparation of pyrimido-fused diazepines. In this context, a number of new 6-amino and 6,8-diamino-4-aryl-2,3-dihydropyrimido[4,5- >][l,4]diazepines were synthesised by the highly regioselective condensation of 4,5,6-triaminopyrimidine and 2,4,5,6-tetraaminopyrimidine respectively with 3-dimethylaminopropiophenones <00JHC401>. 

Two methods are available for the synthesis of 8-C-gly-cosyladenines. A particularly mild method consists in the treatment of 5-amino-4-cyano-2-C-glycosylimidazoles, such as 289a, with formamidine acetate.214 In this way, Igolen and coworkers208,209,211 prepared the C-nucleosides 296 and 299. An alternative synthetic approach to this class of compound involves the treatment of a 2,5-anhydrohexonic acid (such as 15 or 129) with 4,5,6-triaminopyrimidine, followed by cyclization to the nitrogen he-... 

Similarly, open chain C-nucleosides of adenine have been prepared by condensing 4,5,6-triaminopyrimidine with aldonic acids (or aldonolac-tones) of various chain-lengths. The amides (102) first formed were thermally cyclized, affording the 8-(hydroxyalkyl)adenines (103) in rather low yields (119). 

An even more reactive intermediate for the introduction of an 8-oxo group is phosgene which will frequently produce the desired compound by reaction of a diaminopyrimidine in aqueous sodium hydroxide solution at room temperature. In this way 4,5,6-triaminopyrimidine gave the 8-oxopurine (269 Scheme 86) (50JA2587). Chloropurines... 

The isomeric isoguanine (2) is obtained from 4,5,6-triaminopyrimidin-2-ol and formamide. ... 

Triaminopyrimidin-2-ol sulfate (2.84 g, 12 mmol), formamide (35 mL) and 98% formic acid (0.85 mL, 22 mmol) were heated in a bomb tube at 160 °C for 3 h. Upon cooling the crystalline free base deposited yield 1.67g (93%). 

Treatment of 4,5,6-triaminopyrimidine (105) with thionyl chloride affords 7-amino-l,2,5-thiadiazolo[3,4,-d]pyrimidine (106), which can be smoothly transformed into aprinocid (48) through the reaction sequence given in scheme 5 [76]. 

Similarly to 3,3 -diaminobenzidine, other aromatic o-diamines also react with selenium(rV) in HCl medium. The o-phenylenediamine method [30,31] is more sensitive than the DAB method. The following reagents have been proposed for selenium N-methyl-o--phenylenediamine (e = 1.9-10 at 346 nm) [32], 2-aminodiphenylenediamine [33], 4-nitro-1,2-diaminobenzene [34], 4,5-diamino-2,6-dimercaptopyrimidine [35], l,2-diamino-4-chlorobenzene [36], 4,5,6-triaminopyrimidine [37], 3,4-diaminobenzoic acid [38], and 2,3-diaminonaphthalene [39,40]. 

Conversion of 4,5,6-triaminopyrimidine into purines by heating at 160-240 C with an anhydride, a carboxamide or a nitrile gives yields which vary from 36 to 96% [2304]. Aroyl halides in DMF give moderate-to-good yields of 2-aryl-benzimidazoles, and some esters cyclize the triamine similarly [2506, 2979. ... 

Write structures for the purines produced by the following reactions (i) heating 4,5,6-triaminopyrimidine with formamide (ii) treating 2-methyl-4,5-diaminopyr-imidin-6-one with sodium dithioformate, then heating in quinoline. 

The 5-amino derivative of cytosine is reported to inhibit riboflavin synthesis [399]. 4,5,6-Triaminopyrimidine inhibits both synthesis and growth by 60 per cent. 4,5,6-Triamino-2-hydroxypyrimidine inhibits synthesis, but not growth, of riboflavin [400]. 

McLaren 60) observed inhibition of flavin synthe by uracil and ascribed this phenomenon to a competitive inhibition. Goodwin and Pend-lington 52) confirmed the inhibition with large amounts of uracil (50 mg or more N per 100 ml) however, only a slight inhibition of adenine-stimulated flavin production was obtained. Brown el al. 68) observed that 4,5,6-triaminopyrimidine inhibited growth and flavin synthesis of E. ashbyii, while 4,5,6-triamino-2-hydroxypyrimidine and 8-azaxanthine inhibit flavin formation but have little effect on growth. 

Huge success of benzodiazepenes as pharmaceutical scaffolds has prompted preparation and evaluation of het-erocyde-annulated benzodiazepine derivatives. A tandem Michael addition-condensation sequence xmder MW irradiation was also proved to be useful for the synthesis of amino-substituted pyrimidine-fused diazepine derivatives of the type 96 from 4,5,6-triaminopyrimidine and chalcones [57]. Similarly, the pyridine-fused derivatives (97) were prepared xmder MW-assisted solvent and catalyst-free condition [58], Condensation of thiadiazole-annulated phen-ylene diamines with appropriate carbonyl compounds using sulfamic acid as organocatalyst led to the formation of corresponding diazepine derivatives 98 in excellent yields [59] (Figure 4). 

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