Ribonucleoside cyclic 2 ,3 -phosphates preparation

The four 2 3 -cyclic phosphates of the ribonucleosides have been prepared by treatment of ribonucleic acid with potassimn ter<-butoxide or with liquid ammonia in formamide. ... 

Ribonucleoside 2 3 -cyclic phosphate have been prepared by phosphorylation of the 5 -0-acyl derivatives of adenosine and uridine with P -diphenyl P -morpholino pyrophosphorochloridate (63), followed by treatment with dilute ammonium hydroxide. An interesting innovation... 

Ribonucleoside 2 3 -cyclic phosphate are far more liable toward alkali and acid than are the noncyclic phospho-diesters. Hydrolysis of ribonucleoside 2 3 -cyclic phosphate produces a mixture of 2 - and 3 -phos-phates in approximately equal amoimts. Acid- and alkali-catalyzed alcoholysis of these cyclic phosphates also produces a mixture of the 2 -and 3 -alkyl phosphates, - - and the reactions are apparently reversible. " This behavior is a rather general characteristic of five-mem-bered, cyclic phosphates. [[Six-membered, cyclic phosphates, namely (25), (28), and (28a), are relatively more stable. Phosphodiesterases have been employed for the convenient preparation of specific nucleoside 2 - or 3 -phosphates by selective cleavage of a particular 0-P linkage in nucleoside 2 3 -cyclic phosphates. ... 

Modification other atoms or groups. Besides fluorine atoms, other atoms (such as C, N and O) and groups are also used to produce novel sugar-modified nucleoside monophosphates. 2-C-Methyl nucleosides are potential candidates with activity against Hepatitis C virus. Leisvuori et al ° prepared 3,5-cyclic phosphates (25a) and 3,5-cyclic thiophosphates (25h) of 2-C-methyl ribonucleosides as potential antiviral drugs. 

Nucleoside 5 phosphates show no tendency to isomerise, and the 2 and 3 isomers are stable under alkaline conditions. Cyclic 2, 3 ribonucleoside phosphates can be prepared from either the 2 or 3 isomers using a dehydrating agent such as dicyclohexyl dicarbodiimide. The latter reagent can be used to prepare cyclic 3, 5 nucleoside phosphates from nucleoside 5 phosphates. 

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