2,6-Purine-dione synthesis

A new purine ring synthesis has been developed.Treatment of the 6-aminopyrimidine (40) with 4-phenyl-1,2,4-triazoline-3,5-dione in dioxan at room temperature provided the adduct (41) in excellent yield. Fusion of (41) with benzaldehyde at 180 C gave 8-phenyltheophylline (42). A number of 8-aryl analogues were prepared by this method. 

The third synthesis involves cyclization of 8-chloro-7-(2-aminoethyl)purine-dione 238 to 235 (R,R = H). The intermediate 238 was prepared by hydrazinolysis of the 7-(2-phthalimidoethyl) derivative 237 (79S581). A special case of the third ring annulation constitutes a treatment of 8-bis(2-chloroethyl)amino-purinedione 239 with alkali producing a 50 26% mixture of [2,1-/] 240 and [1,2-e] 241, respectively (85JHC105) (Scheme 71). 

Xanthates. See Carbonodithioates 9/f-Xanthene, 9-chloro-9-phenyl- pixyl O-protection with, 341-324 Xanthine = 3,7-dihydro-ltf-purine-2,6-dione synthesis and methylation, 306 Xanthine alkaloids pr., 290 caffeine, 306... 

Thiazolo[5,4-d]pyrimidine, 2,5,7-trichloro-nucleopfulic substitution, 6, 686 Thiazolo[3,2-a]pyrimidine-5,7-diones IR spectra, 6, 672 Thiazolopyrimidines synthesis, 5, 572, 574, 578 Thiazolopyrimidines, amino-purine synthesis from, 5, 591 Thi azolo[3,2-ajpyrimidines synthesis... 

The synthesis of the 2-triazolylpyrimido[l,2,3-cti]purine-8,10-diones 172 and 173 was achieved using the 1,3-dipolar cycloaddition of azides with the terminal... 

Pyrimidine-4,6(lH,3H)-dione, 5-ethyl-2,5-dihydro-2,5-diphenyl-synthesis, 3, 108 Pyrimidine-2,4( 1 H,3H)-diones thiation, 3, 89 Pyrimidine-4,5-diones purine synthesis from, 5, 582 Pyrimidine-4,6-diones tautomerism, 2, 27... 

The heteroaromatic betaines, [l,3,4]thiadiazolo[3,2-a]pyrimidine-5,7-diones (753), which are isoconjugate with methylated xanthines, are in the same way as the latter found to be inhibitors of cyclic AMP phosphodiesterase (78JPS1762). The N-/3-D-ribofuranosyl nucleoside (754) inhibits the synthesis of RNA and DNA but not of protein. The primary blockade is in the synthesis of purine nucleotides (79MI42902). RNA synthesis is also inhibited by [l,3,4]thiadiazolo[3,2-a]pyrimidines of structure (755). The activity is attributed to the chemical reactivity at C-2 leading to reactions with an SH or OH group in RNA polymerase (80ABC1923). Compounds with the 7-oxo formula (756) are claimed to be useful as immune enhancers (78GEP2712932). 

The synthesis from triazoles that, in spite of the poor yield (19%), most shaped future practice was that of Yamada who, by heating 4-amino-l,2,3-triazole-5-carboxamide (73a) with urea (165°C, 5 h), obtained 8-aza-purine-2,6-dione (74) plus the intermediate 4-ureido-l,2,3-triazole-5-car-boxamide. 

A methodology for the synthesis of analogs of asmarine, marine alkaloids with a unique tetrahydro[l,4]diazepino[l,2,3-g,h]purine 120 (THDAP) strueture has been developed. Three cyclization methods were applied for the preparation of the 9,9-disubstituted 10-hydroxy-THDAP system aminomereurization, iodocyclization and acid-catalyzed cychzation <05JOC199>. A series of 2-phenyl[l,2,3]triazolo[l,2-a][l,2,4]benzotriazin-l,5-diones 121 have been synthesized and identified as affinity central benzodiazepine-receptor ligands <05JMC2936>. 

Hie cyclic anhydride (80.4) reacts with trimethylsilyi azide under anhydrous conditions to give a mixture of I,3-oxazine-2,6-dione isomers, which was used without further purification to synthesis several extended purines. Reaction with formamidine acetate in DMF in effect replaced the furandione ring by a pyrimidinone. Cyanamide produced a new fiued 2-aminopyrimidin-4-one [in (80.5, R = NH )], while urea led to a pyrimidinedione. Isatoic anhydride similarly yields 2-aminoquinazolin-4-one on treatment with cyanamide-DMF. 

AI3-52268 CCRIS 994 3,7-Dihydro-1H-purine-2,6-dione 2,6-Dk)xo-1,2,3,5tetrahydropurine 2,5Dioxo-purine EINECS 200-718-6 EPA Pesflcide Chemical Code 116900 Isoxanthine NSC 14664 Pseudoxanthine Purine-2(3H),6(1H)-dione Purine-2,6-diol 1H-Purine-2,6-diol 9H-Purine-2,6-diol 1H-Purine-2,6-dione, 3,7-dihydro- 2,6(1,3)-Purinedion Purine-2,5(1H,3H)-dione 9H-Purine-2,5(1H,3H)-dione USAF CB-17 XAN Xanth-ic oxide Xanthin Xanthine. Used in organic synthesis and medicine. Yellowish powder soluble in H2O (0.007 g/100 ml at 25", 0.07 g/100 ml at 100"), less soluble in EtOH. Am. Bbrganics Dajac Labs. U.S. BioChem. 

Fused pyrimidine-2,4-diones are important heterocyclic pharmacophores examples include natural purine bases, alkaloids, and pteridines. Benzo derivatives in this series (quinazoline-2,4-diones) bear ample precedence as potent ligands and inhibitors of receptors and enzymes of pharmaceutical interest. Based on these precedents, Gordeev et al. reported a solid-phase protocol for the synthesis of fused pyrimidine-2,4-diones. 

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