L//-Purine-2,6,8

CN 3,7-dihydro-8-[(2-hydroxyethyl)methylamino]-l,3,7-trimethyl-l//-purine-2,6-dione... 

CN 7-[2-(diethylamino)ethyl]-3,7-dihydro-l,3-dimethyl-l//-purine-2,6-dione monohydrochloride... 

Methyl-l//-purine, see Atrazine Methylpyrene, see Bis(2-ethylhexyl) phthalate... 

Caffeine Caffeine [l,3,7-trimethyl-l//-purine-2,6(3/7,7//)-dione], molecular formula C8H10N4O2, is a xanthine (purine) alkaloid, found mainly in tea leaves Camellia sinensis) and coffee beans (Coffea arabica). Caffeine is sometimes called guaranine when found in guarana (Paullinia cupana), mateine when found in mate (Ilex paraguariensis) and theine when found in tea. Caffeine is found in a number of other plants, where it acts as a natural pesticide. It is odourless white needles or powder. Apart from its presence in the tea and coffee that we drink regularly, caffeine is also an ingredient of a number of soft drinks. 

The complex [(HLJZnCUJ (L = purine) has been shown to possess the tetrahedral structure (80) (Zn—Cl, 2.226-2.254 A Zn—N, 2.054 A).548 The interaction of 7-azaindole (81) with zinc chloride has been investigated, and the products [Znl CU] (Zn—Cl, 2.231, 2.212 A Zn—N, 2.063, 2.038 A) and [LH]2[ZnCU] have been structurally characterized.548 Complexes of zinc with cytosine,549 adenosine triphosphate550-552 and other purines553 have been investigated, and a crystal structure of the complex [ Zn(bipy)(H2ATP) 2] 4H2O551 has been described. 

H-Pyrido[2,l-/]purine-9-carboxylic acid, 7-oxo-methyl ester, 5, 566 Pyrido[2,3-6]pyrazine, amino-nucleophilic attack, 3, 253 Pyrido[2,3-6]pyrazine, 6-chloro-reactions... 

The reaction of adenosine, and some other derivatives, with DMAD has been shown to yield a mixture of different pyrimido[2, l-/]purines depending on the reaction conditions. The kinetically favoured products (80) usually crystallise from the reaction medium, but if they are soluble then the thermodynamically favoured products (81) result via a Dimroth rearrangement 95H(41)1197],... 

Aryl-7,8-diamino-1,2,4-triazololl, 5-c]pyrimidines (97 R= H) selectively acylate on the 8-amino group to give the amides (97 R= R CO) which cyclise on heating with PPA to yield 2-aryl-8-fIuorobenzyl-l,2,4-triazolo[5,l-/]purines (98) [94JHC1171],... 

CnH 5N02 727-28- ) see Isoprenaline 7-[2-[2- (3,4-dihydroxyphenyl)-2-oxoethyl](phenylme-thy l)amino jcthy 11-3,7-dihydro-1,3-dimethyl-l//-purin-2,6-dione... 

Natural cytokinins are. / /-substituted adenine derivatives. The N6 side chain is either isoprenoid or aromatic (Figure 10), with the former occurring in greater abundance than the latter. The prenyl side chains vary in the presence or absence of a hydroxyl group and the stereoisomeric position. Common active isoprenoid cytokinins are isopentenyladenine (iP /V6-(A2-isopentenyl)adenine), trans-zeatin (tZ / / -(4-hydro.xyisopentenyl)adenine (A)-2-methyl-4-(1 //-purin-6-ylamino)but-2-en-l -ol), ax-zeatin (cZ (Z)-2-methyl-4-(l//-purin-6-ylamino)but-... 

Heteroxanthine l//-Purine-2,6-dione, 3,7-dihydro-7-methyl- Maleic acid 2-Butenedioic acid, (Z)-... 

Isocaffeine l//-Purine-2,6-dione,3,9-dihydro-l,3,9-trimethyl- Naphthalic acid 1,8-Naphthalenedicarboxylic acid... 

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