Steinmaus, H., Department of Chemistry, Weizmann Institute of Science, Rehovot, Israel, Stiftung-Volkswagenwerk
Rosenthal, I., Department of Chemistry, Weizmann Institute of Science, Rehovot, Israel
Elad, D., Department of Chemistry, Weizmann Institute of Science, Rehovot, Israel

Photochemical- and γ-ray-induced reactions of purines and purine nucleosides with alcohols are described. The reactions of 6-substituted and 2,6-disubstituted purines resulted in substitution of an alcohol moiety for the hydrogen atom at C-8, while with 2-aminopurine a primary attack took place at the C-6 position of the purine system. Yields of up to 80% were obtained. A free-radical mechanism is proposed for the reactions, and the following order of reactivity of the various sites in the purine system toward the alcohol-free radicals has been found: C-6 > C-8 > C-2.