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

Abstract

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.

Synthesis of Isotopically Labeled P-Site Substrates for the Ribosomal Peptidyl Transferase Reaction

“…18,19,20,21 Hogencamp et al synthesized [3'/2'- 18 O] adenosine by condensation of adenine with ribosyl chlorides to produce an isotope enrichment of 27%-33%. 18 Reversible hydration (HCl/H 2 18 O) of a 3'-ketouridine derivative followed by reduction (NaBH 4 ) and separation from the xylo epimer (major) gave [3'- 18 O] uridine in low yield.…”

“…Using this strategy, Jiang C. et al reported the synthesis of 2'-18 O-adenosine; however they had difficulty during triflation for the synthesis of [3'- 18 O] adenosine, which was finally prepared via an epoxide intermediate. 20 For pyrimidine nucleosides, the inversion can be realized by formation of 2,2'-or 2,3'-anhydronucleosides, 19,21 We initially attempted to prepare the [3'-18 O] adenosine according to a reported procedure via an epoxide intermediate. 20 The epoxide 17 was prepared as reported.…”

Insight Into the Inhibition of Ribonucleotide Reductases by 2'-chloro-2'-deoxynucleotides and 2'-azido-2'-deoxynucleotides: Biomimetic Studies with Model Substrates

“…144 It is evident from Figure 26 that the ESR characteristics (e.g., overall hyperfine splitting, g-value at the center, lineshape) of the spectra obtained from the commercially available 2'-AZdU and the in-house synthesized 2'-AZdC samples are quite identical. We note here that the central doublets in Figure 26A are assigned to the uracil anion radical (U•¯, black) and cytosine anion radical (C•¯, blue) and the ESR characteristics (e.g., overall hyperfine splitting, g-value at the center, lineshape) of these doublets are identical to the spectra of U•¯ and C•¯ reported in the literature.…”

Biomimetic Modeling of the Nitrogen-centered Radical Postulated to occur during the Inhibition of Ribonucleotide Reductases by 2'-Azido-2'-deoxynucleotides.

“…167,168 As a result of the observed instability of the sulfinyl group in 139, I also synthesized 2',2-anhydrouridine convienniently by treatment of uridine with diphenyl carbonate 169 Addition of azide 165,168 was also achieved using sodium azide in hexamethylphosphoramide (HMPA) at 150 o C in the presence of benzoic acid, which provided 141 in 30 min in a better yield of 56%. The latter method of azidation, however, also yielded the undesired 2'-arabinouridine byproduct (~40%).…”