Uridine-3 -benzyl phosphate

NudeosideSy Nucleotides, and their Derivatives.—3, 5 -Di-0-acetyluridine/ 5-0-acetyl-l -(2-deoxy-a-D-cryt/iro-pentofuranosyl)uracil/° 2-thiouridine, 4-deoxy-3-deazauridine/° S-nitrouridine, 2, 3 -C -isopropylideneuridine, 2, 3 -0-(S)-methoxymethyleneuridme, ° the cyclonucleosides (653 R = H and Me), 0 3 2 -0-acetyluridine 3, 5 -(benzyl phosphate)/ (uridine 5 -phos-phate)(2,2 -dipyridylamine)copper(ii). ... 

The favored formation of a nucleoside 3 -(alkyl phosphate) was observed on treating the diphenyl phosphate anhydride of uridine 2, 3 -cyclic phosphate with benzyl alcohol.273 In a somewhat related reaction, on treatment with dicyclohexylcarbodiimide in aqueous pyridine, adenosine 2 (3 )-phosphate gave, initially, the 2, 3 -cyclic phosphate, which, on further reaction with the diimide, gave a mixture of the N-phosphonourea nucleoside 44 and its 2 -isomer, in unequal amounts.269 This type of reaction does not seem to occur with... 

The possibility that, during the alkaline hydrolysis of ribonucleic acid, tri-esters (18) - could be intermediates was ruled out on mechanistic groxmds."f > Furthermore, it was shown that the tri-ester, uridine 2 3 -(methyl phosphate) (18, R = CH3), synthesized by methylation of uridine 2 3 -cychc phosphate with diazomethane, is resistant to ribo-nuclease. f However, it has been observed that, when the benzyl ester of cytidylic acid 6 is partially hydrolyzed in acid, a significant proportion of the o isomer of this phosphoric diester is formed." ) In addition, the dinucleoside phosphates, such as adenylyl-(3 —>5 )-cytidine (14a), are also isomerized to the corresponding (2 - 5 )-dinucleoside phosphates by treatment with acid. " These studies suggest that cyclic triesters (or derivatives thereof) may be intermediates in isomerization of these phospho-diesters in acidic mediiun. 

When 6 -deoxy-5 -iodo-2, 3 -0-isopropylideneuridine (203) is treated with silver dibenzyl phosphate or with silver tribenzyl pyrophosphate, the protected 5 -nucleotide (205, R = benzyl or dibenzyl phosphoric) was obtained after removal of the protecting groups, this gave uridine 5 -phos-phate (206, R = H) and uridine 5 -pyrophosphate (R = POsHa). It is possible that, in the formation of (205) from (203), anhydronucleoside (204) was an intermediate which underwent attack by the phosphoric... 

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