Methylation of Nucleosides with Trimethylsulfonium Hydroxide. Effects of Transition Metal Ions

Article abstract of DOI:10.1021/jo01307a026

The effect of transition metal acetylacetonates on the methylation of ribo- and deoxyribonucleosides with trimethylsulfonium hydroxide was studied.With ribonucleosides the metal complexes promoted O'-methylation at the 2' and 3' positions of the ribosyl group.A comparable effect was not observed in methylation of deoxyribonucleosides.These results are attributed to an increase in the nucleophilicity of the 2'-OH and 3'-OH groups of the ribosides through complex formation with the metal ion; such a complex cannot form with the deoxyribose derivatives.The activity of the metal ions studied for promoting this O'-methylation increased in the order Mn²⁺ < Co²⁺ = Zn²⁺ < Ni²⁺ < Cu²⁺ < Fe³⁺.These M(AA)n also suppressed N-methylation of the purine and pyrimidine rings of adenosine and cytidine.It is suggested that this result may be caused by coordination of the metal ions with ring nitrogens.