Acetonitrile pyrimidine bases

Fig. 10.21. Electrochromatogram of a mixture of purine and pyrimidine bases and their constituents. Conditions capillary, 270 (205) mm x 100 pm i.d., whole capillary packed with 10 pm ODSS mobile phase, 4.8 mM sodium acetate, pH 4.50, containing 40% (v/v) acetonitrile voltage, +20 kV injection, electrokinetic for 2 s at 1 kV. Peaks in order of elution 1, Ura 2, U 3, Thy 4, Cyt 5, C 6,1 7, Ade 8, Gua 9, A 10, G. Reproduced with permission from Zhang and El Rassi [117],...

Purine and pyrimidine bases and their nucleosides (adenosine, adenine, cytidine, cytosine, guanosine, guanine, inosine, thymine, uridine, uracil) ODSS (octadecyl sulfonated silica), 10 pm Acetonitrile . 8 mM sodium acetate, pH 4.5 (40 60) 270 mm x 20.5 pm i.d 205 mm effective lengtl... 

BSA was effective for the derivatization of purine and pyrimidine bases [456] and nucleosides [457]. Bases were silylated by heating at 150°C with BSA—acetonitrile (1 3) for 45 min. It was stated that under these conditions the TMS derivative of guanine can be prepared reproducibly, but both cytosine and 5-methylcytosine provided two peaks. Silylation of nucleosides, including pseudouridine, was carried out by heating at 120°C with a 100-fold excess of BSA for 2 h. With the use of OV-17 as the stationary phase, this procedure was adopted for the determination of the composition of ribonucleic acids. 

A one-pot procedure was developed (2001JHC419) for the synthesis of (2-al-kylthio-4-oxothieno[3,2-[Pg.87]

A new class of iso-4 -thionucleosides 171, with the base moiety at the 2 position, was synthesized from D-glucose by the couphng of l,4-anhydro-4-tliio-D-arabinitol 168 with purine and pyrimidine bases using the Mitsunobu reaction. The reaction gave predominantly p isomers 170 a p 1 6), when acetonitrile was used as solvent. The reaction proceed via competition between a direct Sn2 reaction and an episulfonium intermediate 169. 

Pyrimidine nucleosides. Nucleosides can be obtained directly by heating a suspension of the pyrimidine base with acetobromoglucose and mercuric cyanide in an inert solvent, toluene or acetonitrile.1... 

Intermolecular N-C-C transfragment replacement occurs less widely than the N-C-N replacement. A synthesis of alkyl(aryl)pyrimidines has been published that was based on the replacement of the N-C-C fragment of the pyrimidine ring by an identical sequence of atoms derived from a ketone in the presence of ammonia [94H(38)249]. Heating a solution of 3-methyl-5-nitropyrimidin-4(3//)-one (120) in acetonitrile with cyclohexanone and ammonia gas in a sealed tube at 100°C for 3 hours gave tetrahy-... 

Based on the previously described silver complex [Au2Ag2(Q)f,s)4(MeCN)2 , the same reaction with CuCl in acetonitrile but with addition of an equivalent of pyrimidine leads to the polymeric [CuAu(C6F5)2(MeCN)((J.2-C4H4N2)]n [66]. The polymerization of this complex is produced by covalent copper-pyrimidine bonds. The environment of the copper centers also comprises unsupported gold-copper interactions of 2.8216(6) A and one molecule of acetonitrile, leading to a distorted tetrahedral arrangement (see Figure 6.26). 

Thus, in base-catalyzed reactions of l,3-dimethyl-2,4-dioxo-l,2,3,4-tetrahydropyrimidine-5-carbonitrile with acetonitrile, malononitrile or similar compounds,192,278,279 as well as ketones,277 pyrido[2,3-c/]pyrimidine-2.4(1 //,3//)-diones 1 retaining the urea portion are formed. 

Base modification at the 4-position of pyrimidines leads to loss of base-pairing properties. The thiol moiety in 91 was deprotected after ODN synthesis using 1 M DBU in acetonitrile. The modified oligothymidylate was then cleaved from the solid phase and reacted with N-(2-chloroethylthio)phthalimide to yield 92, which was subjected to further derivatization [264]. Purine base positions accessible for ligand attachment are C-8 of adenosine (93) [265] and C-2 of guanosine (94) [266]. 

The synthesis of (LVII) is accomplished by formylation of p-(acetamido-phenyl)acetonitrile, followed by conversion to the methoxymethylene derivative with diazomethane, condensation with thiourea to give 2-mercapto-4-amino-5-(p-acetamidophenyl)pyrimidine, and oxidation by peroxide, followed by hydrolysis in base to produce (LVII) [347]. Alternatively, 5-phenylcytosine can be nitrated and reduced [348]. 

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