Uridine 2,3-dimethyl

Uracil reacts with hydrazine to give pyrazol-3(2if)-one (944) and urea N-methyl- and dimethyl-hydrazine behave similarly to give the 2-methyl- and 1,2-dimethyl derivatives. The reactions of hydrazines with uridine and related nucleosides and nucleotides is well studied (67JCS(C)1528). The tautomerism and predominant form of uracil are discussed in Section 2.13.1.8.4. 

In contrast to uridine,389 cytidine does not yield a 5 -chloro-5 -deoxy derivative on reaction with N,N-dimethyl(chlorometh-animinium) chloride instead 2,2 -anhydrocytidine is formed.395 However, thionyl chloride or bromide in hexamethylphosphor-amide at room temperature achieves this selective replacement of the primary hydroxyl group of halogen in cytidine, and also in adenosine, in respective yields of 80 and 75% for the chloro compounds, and 55 and 30% for the bromo analogs.396... 

Monomolar benzylation of methyl 2,3-di-0-benzyl-a-D-galactopyranoside in DMF gave 2,3,6-tri-O-benzyl derivative in 73% yield [52], The primary 6-benzyl ether also forms the major part of the monobenzyl fraction obtained from methyl a-D-galactopyranoside or from its p-anomer [53]. Interestingly, position 6 becomes less reactive than position 2 if 3,4-0-isopropylidene acetals is used to protect the other two secondary hydroxyl groups. The ratio of 2- and 6-benzyl ethers was found to be 11 1 in the a-anomer and 2.5 1 in the p-anomer [53] (see also, Ref. [54]). Uridine [55], cyti-dine [56], and 4-(methylthio)uridine [56] also prefer OH-2 over the primary position when benzylated in dimethyl sulfoxide (for other benzylations in this solvent, see Refs. [35, 57]). 

In addition to the antineoplastic activity, camptothecin was found to be an effective inhibitor of adenovirus replication [268, 269] and herpes virus replication [252, 270]. 10-Methoxycamptothecin is about 8-times more potent than camptothecin as an inhibitor of herpes virus [252]. A combination of camptothecin and dimethyl sulphoxide is very effective for the topical treatment of psoriasis [271]. Since, in the goldfish brain, camptothecin blocks RNA synthesis in eucaryotic cells by blocking the incorporation of uridine into RNA, this alkaloid can block the memory of conditioned avoidance and produces no measurable effect on retention of the learned response [272]. 

RNA oligo (5-aminoallyl uridine and 5 -monophosphate modified) Dye, NHS-derivative (powder) Dimethyl sulfoxide (DMSO) Molecular sieves, class 3A... 

Urinary excretion of modified nncleosides, originating from tiansfer-RNA, may be nsed as a biomarker for tnmonrs and AIDS. Dudley et al. [54-57] reported method development for the analysis of urinary nucleosides by LC-MS. Initially, LC-MS conditions were optimized [54]. In positive-ion ESI-MS, detection limits were achieved ranging from 7 pmol for tubercidin to 110 pmol for uridine. Next, a comparison was made between GC-MS, LC-MS on an ion-trap instrament, and capillary LC-MS on a triple-quadmpole instmment [55]. These methods proved complementary rather than that just one could be selected as optimal. Therefore, in the next study [56], all three techniques were applied to identily the unexpected 5 -deoxycytidine in the urine of a patient suffering with head and neck cancer. In another study [57], they demonstrated the detection of dA, 1-methyl-dA, xanthosine, 7V-l-methyl-dG, 7V-2-methyl-dG, 7V-2,7V-2-dimethyl-dG, A-2,7V-2,A-7-trimethyl-dG, inosine, and 1-methylinosine in urine samples from various cancer patients. 

These groups were prepared to examine the relative acid lability to the classic iso-propylidene group. They are formed from the corresponding dimethyl ketals in acetonitrile with CSA as a catalyst in 95%, 88%, 70% yield, respectively. The relative rates for the hydrolysis of the uridine derivatives in TFA/H20/MeOH at 30° were examined and the results are reported in the following table. ... 

Enterobacteria aerogenes can be grown when dimethyl phosphate is the sole source of phosphorus, and under these conditions a phosphodiesterase can be isolated from the micro-organism which utilizes dialkyl esters of phosphoric acid as substrates. Phosphodiesterases which have been isolated hitherto utilize nucleoside 2, 3 - or 3, 5 -phosphates and 4-nitrophenyl esters as substrates. A studyhas confirmed the hypothesis that phosphate binds to uridine phosphorylase before uridine, and that uracil leaves the enzyme before ribose-1 -phosphate. 

As pyrimidine nucleosides are rather stable under acidic conditions, they may be phosphorylated with a mixture of 85% phosphoric acid and phosphorus pentaoxide ( polyphosphoric acid )- The 2, 3 -0-isopropylidene acetals of uridine and of cytidine were treated with polyphosphoric acid for two hours at 60°. After acid hydrolysis, the 5 -phosphates of these nucleosides were obtained in good yield. 2, 3 -0-Benzylidenecytidine was phosphorylated similarly to cytidine 5 -phosphate. The polyphosphoric acid method was also used to convert the 2, 3 -0-isopropylidene acetals of 5-bromouridine, 3-methyluridine, and A -methyl- and A -dimethyl-cytidine into their respective nucleoside 5 -phosphates. 

Reversible addition of ) -thiolethanol to the 5,6-bond in l,3-dimethyl-5-nitrouracil shows 76% of the 6-adduct in the equilibrium in solution. In 5-halo-uracils and -uridines, adduct formation with thiols, including cysteine, may be accompanied by subsequent dehalogenation, as was also the case for bisulfite adducts . 

C Spectra of uridine [105] in dimethyl sulfoxide, pyridine, H2() and I)20 have been recorded (Mansch and Smith, 1973). The chemical shifts of C-2, C-3 and C-5 i.e. the hydroxyl bearing carbons, shift upfield by 5 Hz in going from water to D20 while the other resonances are unchanged within the experimental error of... 

Nucleosides, Nucleotides, Derivatives, and Related Compounds. — 5-Dimethyl-aminouridine, 5-methylaminomethyl-2-thiouridine, 2, 3 -O-isopropylidene-5-methylaminomethyl-2-thiouridine, 2 -deoxy-5-isopropyluridine, 5-amino-2, 5 -dideoxy-5-iodouridine, 5-nitro-l-( 3-D-ribofuranosyluronic acid)uracil, uridine 3 -phosphate, and uridine 5-diphosphate dipotassium salt. ... 

Vinylphosphonates of cytosine, uracil and ara-C have been prepared by Wittig reactions, and intermediates in these syntheses were hydroxylated using AD-mix-a to give the product 196 and the related derivatives of uridine and cytosine, Geminal hydroxyphosphonates 197 (R = Me or H, and with all four nucleobases) have been prepared by addition of dimethyl phosphite or tris-Tms phosphite to 5 -aldehydes. Similar products were obtained from 2, 3 -0-iso-propylidene ribonucleosides, except in the case of adenosine. NMR studies indicated that the major diastereoisomer formed in each case had 5 -R-stereochemistry, and in some cases this was produced in up to 90% d.e. ... 

A variety of NMR spectroscopic methods have been applied to structural and conformational analyses of the following furanose systems sugar em-dimethyl substituted alkenyl ethers, e.g. a-D-xylofuranose derivatives 13 (see Chapter 5 for synthesis), " the diastereomeric 6-chloro-6-deoxy-l,2-0-isopropylidene-a-D-gulofuranose cyclic 3,5-piperididomonophosphates 14, several 4 -thionucleo-sides, 6-formyl- and 6-(hydroxymethyl)-uridine 5 -carboxaldehydes 15 and 16, respectively, and their 2, 3 -0-isopropylidene derivatives, two double-... 

THE QUAHTITAIIVE SEPARATION OF STACKING AND SELF-ASSOCIATION PHENOMENA IN A DINUCLEOSIDE MONOPHOSPHATE BT MEANS OF NMR CONCENTRATION-TEMPERATURE PROFILES 6-N-(DIMETHYL)ADENYLYL-(3, 5 )-URIDINE. 

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