Cyclo-nucleosides

The synthesis of 2 -deoxy-2 -a-fluoro purine nucleosides via cleavage of purine O-cyclo-nucleosides (see Scheme 7.2) has not been reported, presumably for the following reasons [18] (i) the synthesis of purine O-cyclonucleosides is not so easy as that of pyrimidine O-cyclonucleosides (ii) the glycosyl bond of purine nucleosides is rather unstable under severe reaction conditions such as the use of HF and (iii) it is not easy to remove the... 

Ikehara, M. and Maruyama, T. (1975) Studies of nucleosides and nucleotides - LXV Purine cyclonucleosides-26 a versatile method for the synthesis of purine O-cyclo-nucleosides. The... 

A soln. of 3-deazauridine in dimethylformamide treated with diphenyl carbonate and NaHCOg, heated 0.5 hr. at 150° bath temp. 3-deazauridine 2,2 -cyclo-nucleoside. Y 80%. M. J. Robins and B. L. Currie, Chem. Commun. 1968, 1547 ... 

Potassium tert-butoxide 1 2 -Ethylene- from 2,2 -cyclo-nucleosides... 

Structural analogues of the formycins have been reported in a paper describing a general route to 2-glycosylated pyrimidinones (see Scheme 17). Treatment of formycin with iViV-dimethylformamide dineopentyl acetal gave the 2,5 -cyclo-nucleoside as one of the products, and 2, 3 -0-isopropylideneformycin was converted into the 4,5 -cyclonucleoside by way of the 5 -toluene-p-sulphonate. Adenosine deaminase caused deamination of the 2,S -cyclonucleoside only, indicating that the a //-conformation of a substrate is utilized by the enzyme. 

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