Deaza purines

Fig. 44. Common sites for attaching redox- and photo-active groups to nucleosides C5 pyrimidine, C7-deaza-purine, and C8-purine.

Franchetti, P. Cappellacci, L. Grifantini, M. Lupidi, G. No centini, G. Barzi, A. 8 Aza Analogues of Deaza Purine Nucleo sides — Synthesis and Biological Evaluation of 8 Aza 1 deazaadenosine and 2 DeoxyJl aza 1 deazaadenosine. Nucleosides Nucleotides 1992, 11, 1059-1076. 

Dealkylation, of azolium quaternary salts and betaines, 60, 244 Deazaflavines, bent, 55, 192 5-Deazalumazines, see Pyrido[2,3-(/]pyrimidine-2,4-diones Deaza-purines, -flavines, etc., see the systematically-named ring systems 4-Deazatoxoflavins, syntheses, 55, 182 Dechlorination, catalytic, of chloro-[ 1,2.4]triazolo[ 1,5-a]pyrimidines, 57, 125... 

F. Kirpekar, E. Nordhoff, K. Kristiansen, P. Roepstorff, S. Hahner, and F. Hil-lenkamp, 7-Deaza purine bases offer a higher ion stability in the analysis of DNA by matrix-assisted laser desorption/ionization mass spectrometry. Rapid Commun. Mass Spectrom. 9, 525-531 (1995). 

Tubereidin 6-amino-9-p-D-ribofuranosyl-7-deaza-purine, M, 266.25, m.p. 247-248 °C (d.), [a] j -67° (c = 1, 50% acetic acid), a purine antibiotic (see Nucleoside antibiotics) from Streptomyces tubercidicus, and one of the group of 7-deaza-adenine-nucleoside analogs. The N7 of adenine is replaced by a methylene group. T. is biosynthesized from adenosine (Fig.) the C-atoms of the pyrrole ring are derived from a ribose moiety, which is introduced from 5-phosphoribosyl 1-pyrophosphate. As an antimetabolite of adenosine, T. interferes with purine metabolism. T. can also be eonverted into nicotinamide-dea-za-adenine dinucleotide, which inhibits glycolysis. T. is particularly active against Mycobacterium tuberculosis and Candida albicans. 

Boron trichloride selectively cleaves benzyl ether groups on the sugar in the presence of 6-methoxy or 6-methylthio substituents in the base moiety of 7-deaza-purine nucleosides. ... 

This proton is released from the (Nl)lT site of the 7-deaza-purine residue (see Figures 1 and 5). 

Consistent with the experimental data, mutation of the purine base nitrogens, i.e. N, 3N, 7N and 9N, showed that replacement of N, 3N and 9N with CH had little effect on binding affinity whereas a similar replacement of 7N led to a loss of 2.8 kcal/mol. The 0.6 kcal/mol gain in affinity for the 1-deaza and 3-deaza AMP analogues was consistent with the hydrophobic nature of this portion of the binding site cavity and the absence of hydrogen bond donors in the vicinity of either heteroatom. 

Fluoroadenine, 2-chloroadenine, 2-aminoadenine, 2- and 8-aza-adenines, 4-aminopyra7.olo[3, 4-d] pyrimidine and 6-methylpurine are converted to their ribonucleosidesby adenosine phosphoribosyltransferase,and their ribonucleosides are converted to the ribonucleotides by adenosine kinase most of the ribonucleotides are then converted to the di- and triphosphates. A -Aminoadenine, A -hydroxyadenine, A -methyladenine, purine, 7-deaza-adenine, and 7-amino-pyrazolo[4, 3-d] pyrimidine are either not substrates or are very poor substrates for the phosphoribosyltransferase, but their ribonucleosides are excellent substrates for the kinase. The ribonucleotides of purine, 7-deaza-adenine and... 

Deaza analogs of purines continue to be a major topic of interest to heterocyclic chemists, and especially those with a research focus on biological activity. The synthetic approaches divide, nearly equally, between using pyrimidines or pyrroles as precursors. 

Clearly, the most widespread nucleophilic reaction by heteroatoms is alkylation at ring nitrogen atoms. It is unsurprising that the very great interest in nucleosides of pyrrolo[2,3-d]pyrimidines, as deaza analogues of purine nucleosides, dominates this field. Selected examples of this chemistry... 

Unimolecular cyclizations essentially deal with the synthesis of purine-fused diazocines and the corresponding aza- or deaza-analogues. Such cyclizations occur very often with good yields. Other ring constmctions reported are generally... 

Another promising approach to 2 -deoxyribonucleosides with only a slightly modified purine which shows selective base pairing with 2 -deoxythymidinc (dT) and can be incorporated into DNA is represented by compounds of type 10. Here, position 7 of a 7-deazapurine heterocycle is substituted by an alkynyl side chain. Such nucleosides, e.g. 7-deaza-2 -deoxy-7-hex-l-ynyl-adenosine, exhibit strong fluorescence = 275 nm, = 405 nm). ... 

A few deaza- and aza-dA analogues are reported. 3 -Deaza-dA has been used to probe minor groove recognition contacts,as well as its interactions in DNA curvature at A-tracts. 1-Deaza-adenosine, tubercidin, purine and 4-methylindole deoxyribosides have all been used to probe for an essential... 

Purine nucleosides, aza- and deaza analogues of 81 KGS 147. Photochemical reactions of purines 80WCH9. 

The effects of bromo and iodo substituents in the major groove of DNA have been investigated using 7-halo-7-deaza-8-aza-adenosine and 5-halo-dU derivatives. The incorporation of bromo or iodo groups onto the purine derivative always gave higher stability compared to dA or 7-deaza-8-aza-adenosine. However, there was little effect on substitution of dU. The N -linked 8-aza-7-deaza-... 

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