55003-25-3Relevant articles and documents
Generation of thiyl radicals by the photolysis of 5-iodo-4-thiouridine
Wenska, Grazyna,Taras-Goslinska, Katarzyna,Skalski, Bohdan,Hug, Gordon L.,Carmichael, Ian,Marciniak, Bronislaw
, p. 982 - 988 (2005)
(Chemical Equation Presented) The photochemistry of 2′,3′, 5′-tri-O-acetyl-5-iodo-4-thiouridine (3) in deoxygenated 1:1 CH 3CN-H2O pH 5.8 (phosphate buffer) solution has been studied by means of steady-state and nanosecond laser flash photolysis methods. Under steady-state irradiation (λ ≥ 334 nm), the stable photoproducts were iodide ion, 2′,3′,5′-tri-O-acetyl-4-thiouridine (4), and two disulfides. The disulfides were the symmetrical bis-(2′,3′, 5′-tri-O-acetyl-5-iodo-4-thiouridine) (5) and unsymmetrical 6, which contains both 4-thiouridine and 5-iodo-4-thiouridine residues. The formation of the dehalogenated photoproduct suggests that C(S)-I bond cleavage is a primary photochemical step. Attempts to scavenge the resulting C(5)-centered radical by suitable addends, bis-(N-α-acetyl)cystine-bis-N-ethylamide or benzene, were unsuccessful. Analysis of the photoproducts formed under these conditions showed that the S-atom is the reactive center. The photoproduct 4, obtained by irradiation of 3 in CD3-CN-H2O, followed by reversed-phase HPLC isolation using nonlabeled eluents, did not contain deuterium. An analogous experiment performed in CH3CN-D2O gave deuterated product 4-d with 88% of the deuterium incorporated at C(5). Transient absorption observed upon laser excitation (λ = 308 nm) of 3 was assigned to the 4-uridinylthiyl radical on the basis of the similarity of this spectrum with that obtained upon laser photolysis of the disulfide: bis-(2′, 3′,5′-tri-O-acetyl-4-thiouridine) 14. On the basis of the results of steady-state and laser photolysis studies, a mechanism of the photochemical reaction of 3 is proposed. The key mechanistic step is a transformation of the C(5)-centered radical formed initially by C(5)-I bond cleavage into a long-lived S-centered radical via a 1,3-hydrogen shift. Theoretical calculations confirmed that the long-lived S-centered radical is the most stable radical derived from the 4-thiouracil residue.
Systematic assignment of NMR spectra of 5-substituted-4-thiopyrimidine nucleosides
Zhang, Xiaohui,Wang, Jian,Xu, Yao-Zhong
, p. 523 - 529 (2013/09/02)
Unambiguous characterization of 5-substituted-4-thiopyrimidine nucleosides (ribonucleosides and 2'-deoxynucleosides) was performed using NMR spectroscopy. Assignments of all proton and carbon signals of 5-bromo-4-thiouridine and related nucleosides were systematically carried out and firmly established by COSY and HMQC techniques. The NMR data of various 4-thiopyrimidine nucleosides are compared, and the key contributing factors discussed. The approach presented here is applicable to other modified nucleosides and nucleotides, as well as nucleobases. Copyright
Thionation using fluorous Lawesson's reagent
Kaleta, Zoltan,Makowski, Brian T.,Soos, Tibor,Dembinski, Roman
, p. 1625 - 1628 (2007/10/03)
Thionation of amides, 1,4-diketones, N-(2-oxoalkyl)amides, N,N-acylhydrazines, and acyl-protected uridines with the use of a fluorous analogue of the Lawesson's reagent leads to thioamides, thiophenes, 1,3-thiazoles, 1,3,4-thiadiazoles, and acyl-protected 4-thiouridines. The isolation of the final products in high yields is achieved in most cases by a simple filtration (fluorous solid-phase extraction).
