1.2.4- Triazoles of 2-amino-5-

This is seen during the nitration of PATO (99), which on treatment with a mixture of nitric acid in acetic anhydride at 40 °C for 30 minutes yields the A-nitro product (106), whereas the same reaction at 60 °C for 1.5 hours yields the C-nitro product (107). An explosive known as PANT (109) has been prepared from the reaction of 4-amino-1,2,3-triazole (108) with picryl chloride followed by C-nitration of the 1,2,3-triazole ring with mixed acid at room temperature. ... 

When 7-, 8-, or 9-methyl- or 8- or 9-benzyl-8-azapurines were set aside in aqueous N hydrochloric acid (25 °C, about 1 day), they were completely hydrolyzed to the 1-, 2-, or 3-methyl, or 8- or 9-benzyl derivatives, respectively, of 4-amino-1,2,3-triazole-5-carbaldehyde, as in 28 29. A methyl... 

Day s recent publication of a facile synthesis of 4-amino-1,2,3-triazole-5-carboxamide (73a) and its 3-benzyl derivative (from cyanoacetamide and benzyl azide). ... 

In 1968, the scope of the formamide condensation was greatly expanded by discovery of practical syntheses for the 1- and 2-methyl derivatives of 4-amino-1,2,3-triazole-5-carboxamide. These, for the first time, made possible the direct preparation, and in excellent yields, of 7- and 8-alkyl-substituted 8-azapurines. These new triazoles also underwent condensation with (an excess of) urea and thiourea (175°C, 1 h, no solvent) to give the correspondingly methylated derivatives of 8-azapurine-2,6-dione (64-89% yield) and 2-thioxo-8-azapurin-6-one (55% yield), respectively. ... 

Albert, A., 4-Amino-1,2,3-triazoles, 40, 129 The Chemistry of 8-Azapurines( 1,2,3-Triazolo[4,5-d]pyrimidines), 39, 117 Annelation of a Pyrimidine Ring to an Existing Ring, 32, 1 Covalent Hydration in Nitrogen Heterocycles, 20, 117. 

Aminochromes, 5, 205 Aminomethylenemalonates and their use in heterocyclic synthesis, 54 4-Amino-1,2,3-triazoles, 40, 129 Anils, olefin synthesis with, 23, 171 Anionic cr-adducts of heterocycles, 34, 305 Anions, ring-opening of five-membered heteroaromatic, 41, 41 Annelation of a pyrimidine ring to an existing ring, 32, 1... 

Tandem azidination- and hydroazidination-Hiiisgen [3 +2] cycloadditions of ynamides are regioselective and chemoselective, leading to the synthesis of chiral amide-substituted 1,2,3-triazoles <06OBC2679>. A series of diversely l-substituted-4-amino-1,2,3-triazoles 132 were synthesized by the copper-catalyzed [3+2] cycloaddition between azides 130 and ynamides 131 <06T3837>. 

Azapurine and 1,1-dimethylhydrazine, in water, (room temp, 18 h) furnished 4-dimethylhydrazonomethylenamino-1,2,3-triazole-5-carbalde-hyde dimethylhydrazone (47a). 8-Azapurin-2-one and -2-thione similariy gave the 4-ureido (48a) an(J 4-thioureido (48b) analogs (yields, 63 and 77 %, respectively). 2-Amino-8-azapurine did not react with this reagent, but with hydrazine it produced a 90% yield of 4-hydrazonomethylenamino-1,2,3-triazole-5-carbaldehyde hydrazone (47b). On the other hand, 8-azapurine and its 2-oxo and 2-thioxo derivatives underwent a 2 1 reaction with hydrazine (under the same conditions) to give the azines 49a, b, c, respectively, in 72-88% yields. ... 

Amino-1,2,3-triazole analogs of 4-aminoimidazole-5-carboxamide (4), which is a necessary intermediate for the synthesis of purines in all forms of life, have proved to be valuable inhibitors in experimental biology (see Section V). 

The proportion of tautomers in 1,2,3-triazole (the parent molecule), as ascertained by H NMR (300 MHz), has been found to vary with concentration, temperature, and solvent [84JCS(P2)1025]. No similar study has been made of the 4-amino-1,2,3-triazoles, but crystallographic studies (see Section II,A) have revealed preferred sites of attachment of the ring-bound mobile hydrogen atom. However, crystal studies do not necessarily indicate the equilibria attained in solution. NMR and UV spectra of Sa revealed the presence of three tautomers, the proportions of which depended on the polarity of the solvents (75G583) (no assignments were made). 

S-aminocrotonate, as supported by such canonical forms as MeC(= NH2)-C=C(0 )0Et (71T5873). The 260-270-nm peak in the UV spectra of 5-carbonyl-substituted 4-amino-1,2,3-triazoles is accompanied by another peak near 220 nm, which arises from transitions across the triazole ring. 

A table of carbonyl-stretching frequencies is available for 4-amino-1,2,3-triazole-5-carboxamide (and derivatives) variously acetylated on a ring-nitrogen atom, on the 4-amino group, or on the amide group [71JCS(C)706]. 

The formamide reaction has been successfully used to convert a 2-amino-pyridine-3-carboxamide to pyrido[2,3-d]pyrimidin-4-ones (see 3)220 3-aminopyrazole-4-carboxamide (see 15) to pyrazolo[3,4-rf ] pyrimidin-4-ones (see 16)118 4-aminopyrazole-3-carboxamide to pyrazolo[4,3-d]pyrimi-din-7-ones (see 17)221 many 4-amino-1,2,3-triazole-5-carboxamides (see 20) to 8-azapurin-6-ones (see 21)157,217-222—226 and 4-aminoimidazole-5-car-boxamides (see 18) to purin-6-ones (see 19).124-202-227 228 Secondary amines are suitable starting materials, as in the conversion of 4-amino-l,2,3-triazole-5-(jV-methyl)carboxamide and its 3-benzyl63 and... 

Thiourea has been used similarly to prepare, at 175°C (3 hr) up to 205°C (20 min), good yields of annelated 2-thioxopyrimidin-4-ones such as 8-methyl-2-thioxo-8-azapurin-6-one (156) from 4-amino-1,2,3-triazole-5-car-boxamides (see 20),254 as well as pyrazolo[4,3-d]- and pyrazolo[3,4-d]pyri-midinediones from the appropriate aminopyrazolecarboxamides (see 15) 24,221 and thieno[2,3-d]pyrimidine-2,4-diones (see 12) from 2-amino-thiophene-3-carboxamide.25 5... 

Condensation of amidines with 4-amino-1,2,3-triazole-5-carboxamides (341) yields 2-substituted 8-azapurin-4-ones (342) and supplements a similar ring-closure of the amino-amides with amides (Scheme 131). ... 

In an attempt to study triazole analogs of the a-amino adds as an-timetabolites, Sheehan and Robinson prepared alanine containing such a substituent (1.3-3) along with a series of 4-substituted 1,2,3-triazole intermediates. The best route (Eq. 30) was discovered after several alternatives were investigated. 

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