<sup>18</sup>O Labeled Nucleosides. 2. A General Method for the Synthesis of Specifically Labeled Pyrimidine Ribonucleosides<sup>1</sup>

Solsten, R. Thomas; McCloskey, James A.; Schram, Karl H.

doi:10.1080/07328318208079402

Nucleosides and Nucleotides

1982

DOI: 10.1080/07328318208079402

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¹⁸O Labeled Nucleosides. 2. A General Method for the Synthesis of Specifically Labeled Pyrimidine Ribonucleosides¹

R. Thomas Solsten

James A. McCloskey

Karl H. Schram

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Cited by 7 publications

(1 citation statement)

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“…C. D. Poulter provided [3-15N]uracil, the synthesis of which was previously reported [I8]. [02_ 18 0 IUrid in e and [5,6-ZH z]uridine were synthesized in this laboratory by K. H. Schram in conjunction with earlier work [19,20]. [04_ 180]Uridine and [4-13C,04.…”

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Collision-induced dissociation of uracil and its derivatives

Nelson

McCloskey

1994

J. Am. Soc. Mass Spectrom.

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The collision-induced dissociation of protonated uracil has been studied by tandem mass spectrometry using models extensively labeled with stable isotopes, and derivatives of the kinds found in nucleic acids. Following collisional activation at 30 eV translational energy, protonated uracil dissociates through two principal pathways which do not occur in electron ionization mass spectra: (1) elimination of NH3 almost entirely from N-3, followed by loss of CO from C-4, 0(4); (2) loss of H2O, equally from 0(2) and 0(4). Elimination of HNCO, also the principal dissociation process from odd-electron molecular ions, proceeds primarily by loss of N-3, C-Z, O(2) and 10% from N-l, C-Z, 0(2). Several secondary dissociation products are formed with quantitative site specificity of skeletal atoms: C,HO+ (4-C0, C-5, C-6); H2CN+ (N-l, C-6); C2H2+ (N-l, C-5, C-6). First-step dissociation reactions are interpreted in terms of pyrimidine ring opening at likely sites of protonation after collisional activation of MH+. Collision-induced dissociation mass spectra of uracils with structural themes common to nucleic acids (methylation, replacement of 0 by S, C-5 substitution) follow analogous reaction paths which permit assignment of sites of substitution, and exhibit ion abundance changes attributed to differences in substituent basicity and electron density.

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Collision-induced dissociation of uracil and its derivatives

Nelson

McCloskey

1994

J. Am. Soc. Mass Spectrom.

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Synthesis and ¹⁵N‐ and ¹⁷O‐NMR Spectra of 5‐Methyl(¹⁵N₂)[O²,O⁴‐¹⁷O₂]uridine (= (¹⁵N₂)[O²,O⁴‐¹⁷O₂]Ribosylthymine)

Amantea

Walser

Séquin

et al. 1995

Helvetica Chimica Acta

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The 5-methyl('5N2)[02,04-1702Juridine (= (15N2)[02,04-'70,]ribosylthymine; 15) was synthesized and analyzed by I5N-and 170-NMR spectroscopy. (I5N,)Urea was condensed with 2,3-dibromo-2-methylpropanoyl chloride (3) and cyclized to form ("N,)thymine (5) After glycosidation, the "0 isotopes were introduced in two separate steps: hydrolytic ring opening of 2,5'-anhydro derivative 9 and hydrolysis of 3-nitro-1H-l,2,4-triazole derivative 12 with labelled water in the presence of a strong base. The "N-and I70-NMR spectra (Fig.) of 15 in phosphate-buffered water serve as references for heteronuclear NMR spectra of labelled RNA fragments.The chemical shifts of both "N and I7O nuclei are known to be sensitive to the formation of H-bonds. When incorporated into the bases of RNA, these nuclei might serve as a monitoring device for folding and unfolding processes. Doubly labelled 5-methyluridine ( = ribosylthymine) was chosen for a first analysis by "N-and I70-NMR spectroscopy on the nucleoside level (see also following paper). Protection of the 2 -and 3'-OH groups of 7 (-+ 8) and cyclization of the 5'-OH group with one base carbonyl group yields 2,5'-anhydro derivative 9. The first I7O isotope is introduced at C(2) through the hydrolysis of 9 with a Na[170]H/H2['70] solution giving the doubly labelled nucleoside derivative 10 [3]. Compound 10 is monomethoxytritylated to 11. The introduction of the second l7O isotope at C(4) is accomplished in three in situ steps to avoid loss of material owing to unnecessary purification procedures. The introduction of a leaving group, 3-nitro-lH-l,2,4-triazole [4], proceeds efficiently (+ 12), as judged by TLC and 'H-NMR. Subsequent hydrolysis with less than 2 equiv. of H,[I70] yields compound 13. Detritylation furnishes isopropylidene derivative 14 in 68 YO overall yield over those steps. Final deprotection with CF,COOH affords the target compound 15.Nucleoside 15 ('rT) is characterized by mass, and I7O-and I5N-NMR spectroscopy (Fig.). Comparison of the mass spectra of nucleosides 7, 10, and 15 reveals that the isotope-substitution efficiencies are 92% (34 atom-% "0) for the first and 80% (29.7

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Stereodefined Synthesis of O3‘-Labeled Uracil Nucleosides. 3‘-[¹⁷O]-2‘-Azido-2‘-deoxyuridine 5‘-Diphosphate as a Probe for the Mechanism of Inactivation of Ribonucleotide Reductases

et al. 2002

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Thermolysis of a 2'-[(16)O]-O-benzoyl-[(17)O]-5'-O-(tert-butyldimethylsilyl)-O(2),3'-cyclouridine derivative gave the more stable 3'-[(17)O]-O-benzoyl-[(16)O]- 5'-O-(tert-butyldimethylsilyl)-O(2),2'-cyclouridine isomer, which was converted into 3'-[(17)O]-2'-azido-2'-deoxyuridine by deprotection and nucleophilic ring opening at C2' with lithium azide. The 5'-diphosphate was prepared by nucleophilic displacement of the 5'-O-tosyl group with tris(tetrabutylammonium) hydrogen pyrophosphate. Model reactions gave (16)O and (18)O isotopomers, and base-promoted hydrolysis of an O(2),2'-cyclonucleoside gave stereodefined access to 3'-[(18)O]-1-(beta-D-arabinofuranosyl)uracil. Inactivation of ribonucleoside diphosphate reductase with 2'-azido-2'-deoxynucleotides results in appearance of EPR signals for a nitrogen-centered radical derived from azide, and 3'-[(17)O]-2'-azido-2'-deoxyuridine 5'-diphosphate provides an isotopomer to perturb EPR spectra in a predictable manner.

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¹⁸O Labeled Nucleosides. 2. A General Method for the Synthesis of Specifically Labeled Pyrimidine Ribonucleosides¹

Cited by 7 publications

References 14 publications

Collision-induced dissociation of uracil and its derivatives

Collision-induced dissociation of uracil and its derivatives

Synthesis and ¹⁵N‐ and ¹⁷O‐NMR Spectra of 5‐Methyl(¹⁵N₂)[O²,O⁴‐¹⁷O₂]uridine (= (¹⁵N₂)[O²,O⁴‐¹⁷O₂]Ribosylthymine)

Stereodefined Synthesis of O3‘-Labeled Uracil Nucleosides. 3‘-[¹⁷O]-2‘-Azido-2‘-deoxyuridine 5‘-Diphosphate as a Probe for the Mechanism of Inactivation of Ribonucleotide Reductases

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18O Labeled Nucleosides. 2. A General Method for the Synthesis of Specifically Labeled Pyrimidine Ribonucleosides1

Cited by 7 publications

References 14 publications

Collision-induced dissociation of uracil and its derivatives

Collision-induced dissociation of uracil and its derivatives

Synthesis and 15N‐ and 17O‐NMR Spectra of 5‐Methyl(15N2)[O2,O4‐17O2]uridine (= (15N2)[O2,O4‐17O2]Ribosylthymine)

Stereodefined Synthesis of O3‘-Labeled Uracil Nucleosides. 3‘-[17O]-2‘-Azido-2‘-deoxyuridine 5‘-Diphosphate as a Probe for the Mechanism of Inactivation of Ribonucleotide Reductases

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¹⁸O Labeled Nucleosides. 2. A General Method for the Synthesis of Specifically Labeled Pyrimidine Ribonucleosides¹

Synthesis and ¹⁵N‐ and ¹⁷O‐NMR Spectra of 5‐Methyl(¹⁵N₂)[O²,O⁴‐¹⁷O₂]uridine (= (¹⁵N₂)[O²,O⁴‐¹⁷O₂]Ribosylthymine)

Stereodefined Synthesis of O3‘-Labeled Uracil Nucleosides. 3‘-[¹⁷O]-2‘-Azido-2‘-deoxyuridine 5‘-Diphosphate as a Probe for the Mechanism of Inactivation of Ribonucleotide Reductases