Using Vorbrüggen's protocol, reaction of persilylated uracil with xylofuranose derivatives having 3beta-oxy-3alpha-alkyl substitution produced both alpha- and beta-nucleosides. Only the beta-nucleosides were formed from substrates having the reverse stereochemistry at C-3 or lacking the 3-alkyl substituent. Participation of the 3beta-oxy substituent in stabilizing the incipient C-1 carbonium io...

Structural characterisation and reactivity of new tetrahedral intermediates based on a highly modular barbituric acid scaffold, formed via chemoselective electron transfer using the SmI2-H2O reagent, are reported. Lewis acid promoted cleavage of bicyclic α-amino alcohols affords vinylogous N-acyliminium ions, which undergo selective (>95 : 5, 1,4 over 1,2) capture with a suite of diverse nucleo...

Structural characterisation and reactivity of new tetrahedral intermediates based on a highly modular barbituric acid scaffold, formed via chemoselective electron transfer using the SmI2–H2O reagent, are reported. Lewis acid promoted cleavage of bicyclic a-amino alcohols affords vinylogous N-acyliminium ions, which undergo selective (>95 :5, 1,4 over 1,2) capture with a suite of diverse nucleop...

Oxidation of uracil (U) and thymine (5-Me-U) are believed to play a role in genetic instability because of the changes these oxidations cause in the ionization constants (pKa values), which in turn affects the base pairing and hence coding. However, interpretation of the experimental evidence for the changes of pKa with substitution at U has been complicated by the presence of two sites (N1 and...

Under the conditions for oxidative degradation, with a 2-fold molar excess of periodate and cyclohexylamine at room temperature, *MP is degraded to inorganic phosphate but fails to release the base. In this latter respect, the parent pseudouridine behaves similarly. Under more drastic conditions, with a prolonged treatment at 4.5” and a 6-fold molar excess of periodate and cyclohexylamine, \kMP...

The ability of 4-thiouracil to strongly absorb UVA radiation and to populate a reactive triplet state in high yield has enabled its use as a versatile photocrosslinker for nearly 50 years. In this contribution, we present a detailed spectroscopic and photochemical investigation of the 2-thiouracil, 4-thiouracil, and 2,4-dithiouracil series in an effort to further advance this chemistry and to s...

The synthesis and enantiomeric features of 2-hydroxymethyl-tetrahydro-oxazolo[3,2-c]pyrimidine-5,7-(4H,6H)-diones (V) are. described. The diazomethane methylation of these bicyclic compounds afforded 2-hydroxymethyl-6-methyl-tetrahydro-oxazolo-[3,2-c]pyrimidine-5,7-(4H,6H)-diones (R)-(XXII) and (S)-(XXII), respectively. For the synthesis of (R)-V and (S)-V the respective 5-bromo-1-(2,3-dihydrox...

From replacement studies (1) and inhibition analysis (2) with microorganisms requiring folic acid, it has been inferred that this vitamin is concerned in the biosynthesis of purines and of thymine. More directly, folic acid has been shown to be involved in nucleic acid synthesis in Lactobacillus casei (3,4). According to Buchanan and Schulman (5), the formation of purine derivatives would seem ...

A series of 23 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine derivatives that were highly potent inhibitors of wild-type human immunodeficiency virus type 1 strain IIIB (HIV-1/IIIB) replication in CEM cells were evaluated against a panel of HIV-1 mutant strains containing the replacement of leucine by isoleucine at position 100 (100-Leu-->Ile), 103-Lys-->Asn, 106-Val-->Ala, 138-Glu-->Lys, 1...