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PubMed2001

Synthesis of pyrrolo[2,1-f][1,2,4]triazine C-nucleosides. Isosteres of sangivamycin, tubercidin, and toyocamycin.

Syntheses of pyrrolo[2,1-f][1,2,4]triazine C-nucleosides are reported. Treatment of pyranulose glycoside with aminoguanidine in acetic acid gave the corresponding semicarbazone in 96% yield. The ring transformation of the semicarbazone in dioxane afforded a 51% yield of 2-amino-7-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)pyrrolo[2,1-f]-[1,2,4]triazine. Vilsmeier formylation of the pyrrolotriazine gave the major product, 5-formylpyrrolo[2,1-f][1,2,4]triazine, in 69% yield. The aldehyde was treated with hydroxylamine hydrochloride in methanol to give aldoximes. Dehydration of aldoxime with trifluoromethanesulfonic anhydride and triethylamine in dichloromethane afforded 5-cyanopyrrolo[2,1-f][1,2,4]triazine in 44% yield. Conversion of the nitrile to the deprotected amide, 2-amino-7-(beta-D-ribofuranosyl)pyrrolo[2,1-f][1,2,4]triazine-5-carboxamide, was accomplished in 96% yield on treatment with 30% H2O2 in ethanol for 1 day at room temperature. Debenzoylation with sodium hydroxide solution produced deprotected C-nucleosides.

Antibiotics, Antineoplastic↗

PubMed1976

Synthesis and biological activity of pyrazolo[3,4,-d]pyrimidine nucleosides and nucleotides related to tubercidin, toyocamycin, and sangivamycin.

The 6-aza analogues of toyocamycin and sangivamycin were prepared as potential cytotoxic agents. The toyocamycin analogue (4-amino-1-(beta-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine-3-carbonitrile) could not be obtained directly from its O-acetylated precursor but was accessible via 4-amino-1-(beta-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine-3-thiocarboxamide. The identity of the nitrile was verified by its ultraviolet, infrared, and mass spectra, and by its conversion to the corresponding 3-carboxamide and thiocarboxamide when treated with water or hydrogen sulfide, respectively. Bioassay of the synthetic compounds in comparison with 4-amino-1-(beta-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine (6-azatubercidin) and 4-amino-2-(beta-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine revealed that the 3-thiocarboxamido derivative was more cytotoxic to the growth of mouse fibroblasts than 6-azatubercidin, effecting killing of 3T6 cells at less than or equal to 1 mug/ml. 4-Amino-1-(beta-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine (but not its 2-ribofuranosyl isomer) was shown to act as a substrate for adenosine deaminase from calf intestinal mucosa with an apparent Km of 125 (vs. 20 for adenosine) and the corresponding 5'-diphosphate of 6-azatubercidin was polymerized by polynucleotide phosphorylase (Micrococcus luteus) in the presence of Mn2+ to afford a homopolymer and copolymers with adenosine. The copolymers directed the binding of [3H]lysyl-tRNA to the A-site of ribosomes from Escherichia coli, but could not be used for the synthesis of polylsine in a cellfree system. The copolymer consiting of adenosine and 6-azatubercidin in a 2:1 ratio was found to form a 1:1 complex with poly(uridylic acid) at 4degreesC.

Antibiotics, Antineoplastic↗

PubMed1996

Tubercidin analogs from the ascidian Didemnum voeltzkowi.

Two new 5'-deoxypyrrolo[2,3-d]pyrimidine (7-deazapurine) nucleosides, 5'-deoxytubercidin and 5'-deoxy-3-bromotubercidin, were identified from the ascidian Didemnum voeltzkowi. Two known anomers of 5'-deoxy-3-iodotubercidin were also purified from the extract. Assignments were made on the basis of 1H and 13C chemical shifts as well as HPLC-MS experiments.

Animals↗

PubMed1964

BIOLOGICAL AND BIOCHEMICAL PROPERTIES OF THE ANALOGUE ANTIBIOTIC TUBERCIDIN.

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Adenine Nucleotides↗

PubMed1986

Oligonucleotide duplexes containing inosine, 7-deazainosine, tubercidin, nebularine and 7-deazanebularine as substrates for restriction endonucleases HindII, SalI and TaqI.

Synthetic hexadecanucleotide duplexes containing a single purine nucleotide analogue in the recognition sites of the restriction endonucleases HindII, SalI and TaqI were used to investigate the restriction site determinants required by these enzymes for sequence recognition and phosphodiester bond cleavage. The enzymes were, in general, unaffected by changes introduced into the minor groove of the helix. SalI was found to be inhibited by the major groove modifications introduced into the fourth position of its recognition sequence GTCGAC. HindII and TaqI were, by contrast, able to cleave the sites containing the analogues at this position. TaqI and, to a lesser extent, HindII could also be shown to tolerate "mismatch analogues" at this site.

Base Sequence↗

PubMed1976