Regioselective arylation of ribose in adenosine and guanosine with the antitumor drug N2-methyl-9-hydroxyellipticinium acetate.

The transformation of the antitumor drug N2-methyl-9-hydroxy-ellipticinium by a peroxidase-hydrogen peroxide system, which has been shown to occur in vivo, leads to an electrophilic quinone-imine derivative. This unstable molecule arylates in vitro purine nucleosides and nucleotides, leading to regioselective adducts substituted only at the 2'-O position of the ribose, as shown by mass spectrometry and NMR. It is likely that an important preliminary step in this reaction is a stacking process between the ellipticinium ion and the purine rings, which might explain this regioselectivity.