a new efficient method for the synthesis of carboacyclic nucleosides as biologically interesting compounds via aza-conjugate addition of pyrimidine nucleobases to a,β-unsaturated esters in the presence of catalytic amount of lioh.h2o (1.2-4.8 mol%) under microwave irradiation is described. this method affords the title compounds in good to excellent yields and in short reaction times.

INTRODUCTION ................................................................. 33 PHYSIOLOGICAL ANTIMUTAGENESIS ........ .................................. 34 Purine Nucleosides (Adenosine, Guanosine, and Inosine) ..... ...................... 34 Caffeine.35 Manganous ions ................................................................. 37 L-Methionine .............................................

Different (±)-4-(3/4-acetoxyaryl)-5-ethoxycarbonyl-6-methyl-3,4-dihydropyrimidin-2-ones have been synthesized and subjected to enantioselective deacetylation reactions mediated by different lipases in organic media. Novozyme 435 in tetrahydrofuran:diisopropyl ether was found to be the catalyst of choice for efficient enantioselective deacetylation of dihydropyrimidinones under study. Further, w...

An isotachophoretic system is described for the separation and identification of urinary purine and pyrimidine bases and nucleosides. For a better discrimination and interpretation of the UV profiles, well-defined non-UV-absorbing substances were introduced as spacers. Treatment of urine samples with purified enzymes before analysis resulted in specific shifts in the metabolite profiles, provid...

Previous studies from this laboratory on the preservation of erythrocytes stored in vitro have shown that the storage lesion, as characterized by the decline in level of organic phosphate esters, may be reversed by incubating the aged cells with certain purine nucleosides (1). Pyrimidine nucleosides were ineffective in this respect, as was the addition of the purine bases and ribose, alone or i...

In order to assemble the sequence, addition of each nucleoside requires four chemical reaction steps and each of these reaction steps is expected to be quantitative (100%). In reality, efficiencies of these reaction steps vary from 97 to 99.9% depending on the reagents, nucleoside building blocks (phosphoramidite) and moisture in the solvent. Depending on the efficiency of each nucleoside addit...