Nucleoside Thiophosphates

Kanaoka, K. Itoh, E. Sato, A. Nomura, and Y. Mizuno, Chem. and Pharm. Bull. 

5 -phosphorothioates however, the yields of product are lower than with (30). 5 -Deoxy-5 -thioinosine phosphate (31) has been prepared by treating 5 -deoxy-5 -iodoinosine (32) with trisodium phosphorothioate.  

Silver ions will oxidatively desulphurize nucleoside and other phos-phorothioates to generate a phosphorylating agent. This reaction has been utilized for the preparation of nucleotide coenzymes and has the advantage that it can be carried out on a large scale without the formation of contaminating symmetrical pyrophosphates. 

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In the mononucleotide area, the past year has been highlighted by the development of novel phosphate-protecting groups and their use in nucleotide and chiral nucleoside thiophosphate chemistry. Concise methodologies have been described for cost effective syntheses of oligonucleotide building blocks, and the collection of unnatural nucleotides reported to have been synthesised has been considerably expanded. 

Nucleoside phosphates are pivotal in a number of important biological processes, and so the detailed mechanisms of the reactivity of these compounds have been widely studied. A recent study has shown that the major product of hydrolysis of the cyclic thiophosphate analogue 25 varies according to pH as shown in Equation (5). The detailed hydrolysis pathway has implications for the use of such compounds as therapeutic agents <2000EJ01987>. 

Uracil and cytosine derivatives of 4-thio-DL-erythrofuranose and adenine and guanine nucleoside analogues of 4-thio-D-ribofuranose, 4-thio-D-xylofuranose, and 5-thio-D-xylopyranose have been reported. Treatment of 2,2 -anhydro-cytosine with phosphorus pentasulphide gave the cyclic thiophosphate derivatives (49), which was used to prepare other 2 -thio-cytidine derivatives. The... 

S-2-carbamoylethyl thiophosphate can be activated with diphenyl phosphorochloridate and the resulting pyrophosphate triester reacted wdth a nucleoside diphosphate to give a... 

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. 

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