1.2.4- Triazoles 3,5-diamino— from

For the preparation of triazolopyrimidines three main types of synthesis are in use. The first of these proceeds from a pyrimidine derivative (especially the 4,5-diamino derivatives) and closes the triazole ring. The second method proceeds, on the contrary, from derivatives of u-triazole to close the pyrimidine ring. The third method finally is one which yields the derivatives through substitution or replacement of substituents in compounds prepared by one of the first-named procedures. 

Boyer and Gunasekaren reported the synthesis of the furazan-based heterocycle NOTO (44), which contains 50 % by mass of nitrogen and is a liquid at room temperature. The flve-step synthesis of NOTO (44) starts from the diazotization of 4,4 -diamino-3,3 -azoxyfurazan (DAAF) (27), followed by reaction with sodium azide to form the diazide (42). Heating the diazide (42) as a solution in acetonitrile induces cyclization to the triazole (43) and this is followed by reduction and oxidation of the remaining azide group to complete the synthesis of NOTO (44). 

Laval and Vignane reported the synthesis of the nitrotriazole (124) from the reaction of 3-nitro-1,2,4-triazole with 3,5-diamino-l-chloro-2,4,6-trinitrobenzene. The nitrotriazole (124) is a useful secondary high explosive, exhibiting high performance and a low sensitivity to impact. 

Direct amination of benzo[l,2-aqueous base with hydroxylamine-0-sulfonic acid gives a mixture of three diamino derivatives and two monoamino derivatives (Equation (15)). The combined yields of diamino and monoamino products are 45% and 48%, respectively. The three diamino derivatives can be separated by fractional crystallization from ethanol <86JOC979>. A-Amination of triazoles can also be achieved by treatment with NaH in DMF followed by O-amino-2,4-dinitrophenol <85TL335> or 0-(mesitylsulfonyl)hydroxyamine (9lJCS(Pl)2045>. 

Arylbenzotriazoles (797) are prepared via 2-nitro- and 2-amino-diphenylamines (Scheme 161). The 2-nitrodiphenylamines (796) are prepared from the appropriate aniline by reaction with 2-fluoronitrobenzene in the presence of KF <808215,85JCS(Pl)2725>. Azo-coupling of 2-amino-1-cyano-azulene (798) with p-tolyldiazonium chloride gives (799) (Scheme 162). Catalytic reduction of (799) quantitatively yields the diamino derivative (800), which on diazotization affords 9-cyano-azuleno[l,2-J]triazole (801) in 77% yield <85TL335>. 

Aminotriazoles which are appropriately substituted at the C(5)-position are important intermediates for the synthesis of 8-azapurines. These reactions have been reviewed <86AHC(39)ll7>. The pharmaceutically useful acyclonucleosides bearing 1,2,3-triazolines and 8-azapurines have been synthesized <888879). 4,5-Diaminotriazoles react with 1,2-dicarbonyl reagents to give 1,2,3-triazolo[4,5- )]pyrazines. 4,5-Diamino-2-phenyltriazole and sulfur monochloride afford the triazolo[4,5-c][l,2,5]thiadiazole (855) <86AHC(40)129>. The synthesis of triazolopyridines from triazoles has been described in a review <83AHC(34)79>. For further applications of substituted triazoles in preparations of complex heterocycles, see Section 4.01.4. 

Apart from imidazol-2-ylidenes (IV), eight other types of carbenes are included in this category imidazolidin-2-yhdenes (III), tetrahydropyrimid-2-yhdene (V)," ° benzimidazol-2-ylidene (VI)," l,2,4-triazol-5-ylidene (VII)," l,3-thiazol-2-yli-denes (VIII), as well as acyclic diamino- aminooxy- and aminothio-carbenes (XI) (Fig. 8.5). 

Potts and McKeough81 have recently obtained several interesting mesoionic azapentalenes 83, 84 by reaction of the appropriate 1,4-dicarbonyl compound with phosphorus pentasulfide. Compounds 83 and 84 can be written as dipolar structures, but participation of sulfur d-orbitals allows nonpolar forms to be envisaged. MO calculations neglecting rf-orbital participation predict the thieno[3,4-c]pyrrole system (84) to be very unstable.430 A related system 86 has been prepared by Japanese workers63 from the diamino-r-triazole (85) and sulfur dichloride. 

Rearrangement of triazolotriazepinones 174 (prepared by the action of ethyl acetoacetate on 4,5-diamino-s-triazoles) has been shown to take place in acetic anhydride to give pyrazolo[3,2-c]-s-triazoles (175). 62 The mechanism of this reaction is being investigated.163 It has been conclusively shown that compounds of structure 174 (not 173 as previously thought164) result from the action of ethyl acetoacetate on 3-substituted 4,5-diamino-s-triazoles.162... 

The intermediate A-anilinoamidino-2-thioureas, which result from the treatment of 3,5-diimino-l,2,4-dithiazolines (thiurets) with phenyl-hydrazine, were reported by Fromm64-88 to cyclize to 3,5-diamino-1,2,4-triazoles. Kurzer and co-workers, who had earlier reported the cyclization of amidinothioureas to 1,2,4-triazoles,67 extended this work to l,3-bis(isopropylideneimino)-2-arylthiocarbamoylguanidines (35),... 

C8H6N8O6 mw3l0.22 N36.13% OB to C02 —67.05% cryst mp 275° (decompn) d 1.85g/cc sol in hot 7-b uty rolac to ne-ethanol mixt Prepn. A soln of 3,5-diamino-1,2,4-triazole (2.48g, 0.025mole) and picryl chloride (2.48g, 0.01 mole) in 50ml of dimethylsulfoxide is heated at 70° for 5 hrs, then poured into 400ml of ice and w. The crude product is collected by filtration and recrystd from 7-butyrolactone-ethanol (treatment with Norite was necessary) to yield 1.86g (60%)... 

Two series of dyes are derived from 3,5-diamino-l,2,4-triazole [1455-77-2, also known as guanazole. The monoazo dyes form red diazadimethine dyes (e.g., 35) after alkylation [88],... 

It should be noted in conclusion that l-amino 4-methyl-5-imino 4,5-dihydro-l//-tetrazole 306 obtained by elimination of I INj from l,5-diamino-4-methyltetrazolium salt (X = N3) 172 (cf. Section 6.07.5.2.1) at 160-185°C decomposes giving HCN, 1,2,4-triazole, and cross-linked products <2005THE168>. 

Dinitro-l,2,4-triazole has been synthesized from 3,5-diamino derivative with sodium nitrite excess [667], and the protocol was proposed for the preparation of 3,5-dinitro-l,2,4-triazole from dicyanodiamide and hydrazine without isolation of 3,5-diamino-l,2,4-triazole. 

Place 300 milliliters of dimethylformamide (DMF) into a flask, and then add and dissolve 4.4 grams of 3-nitro-1,2,4-triazole (obtained in step 2) while stirring the DMF. Stir the DMF mixture for 1 hour at room temperature (while stirring, keep the flask sealed from the air). After 1 hour, place the mixture into a cold water bath, and then add 10 grams of l-fluoro-3,5-diamino-... 

N,N -Dimethylacetamide (DMAc) (Aldrich, HPLC grade) was used without further purification. Acetic anhydride (BDH) was pre-dried over anhydrous sodium acetate. Pyridine (Aldrich, anhydrous) was distilled from KOH prior to use. Poly(maleic anhydride-co-octadec-l-eneXl l) (Polysciences), as a polymeric stabilizer, was used as supplied. Paraffin oil (A.J. Beveridge Ltd., liquid paraffin 5LT) was used as a suspending medium. Pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic dianhydride) (Aldrich) was recrystallized from butan-2-one before use. p-Phenylenediamine (Aldrich) and 2,6-diaminopyridine (Aldrich) were recrystallized from ethanol. 3,5-Diaminobenzoic acid (Aldrich) and 2,5-diaminobenzene sulfonic acid (Aldrich) were recrystallized from water and heated at HOT) under vacuum to remove water. 3,5-Diamino-l,2,4-triazole (Aldrich) and tris(2-aminoethyl)amine (Tokyo Kasei) were without further purification. 

N,N -dimethylacetamide was prepared from pyromellitic dianhydride and the functional diamines, 3,S-diamino-l,2,4-triazole 2,5-diaminobenzoic acid 2,5-diaminobenzene sulfonic acid or 2,6-diaminopyridine. Each pre-polymer solution was then dispersed as droplets in paraffin oil containing poly(maleic anhydride-co-octadec-l-eneXl l) as a suspension stabilizer, and imidization induced at 60C by addition of a mixture of acetic anhydride and pyridine (Figure 1). 

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