Aralkylation of 2'-deoxyguanosine: medium effects on sites of reaction with 7-(bromomethyl)benz[a]anthracene.

Product distributions were determined for reactions between 2'-deoxyguanosine, or its anion, and 7-(bromomethyl)benz[a]anthracene in either acetone/H2O (1:1) or 2,2,2-trifluoroethanol at 50 or 70 degrees C. The exocyclic amino-substituted product, N2-(benz[a]anthracen-7-ylmethyl)-2'-deoxyguanosine, was always the major nucleoside product formed in these reactions, although its yield was higher in reactions involving 2'-deoxyguanosine anion than the neutral nucleoside. Reaction with the anion also led to formation of the 1-substituted 2'-deoxyguanosine and a guanidinoimidazole nucleoside resulting from reaction of 2'-deoxyguanosine at carbon 5. Reactions of 2'-deoxyguanosine anion in 2,2,2-trifluoroethanol are shown to produce significant amounts of the N2-substituted product, which is difficult to prepare by other routes.