Pyrimidines electrochemically-generated

Scheme 1. Structures of pyrimidine dimers (I) electrochemically generated hydrodimer of pyri-midone-2 (II) photochemically generated pyrimidine adducts (III) photochemically generated cyclobutane dimers...

It was previously shown that two reduced forms of NAD, viz. NADH and the dimer (NAD)2, may revert photochemically to the parent, enz3fmati-cally active NAD. Similar photochemical ability has been found for electrochemically generated dimers of pyrimidine and purine derivatives . In the presence of oxygen this photochemical oxidation is accompanied by formation of H2O2, and the superoxide radical O2 is an intermediate in the reaction". ... 

We present here a brief account of the specific dimerization, and other related, reactions undergone by a variety of purine and pyrimidine derivatives, and a number of related compound s, during the course of their electrochemical reduction at the surface of a mercury electrode. A characteristic feature of these reactions is the transfer of an electron to the compound, accompanied, or preceded, by its protonation. The resultant free radicals, generated by a one-electron reduction process, rapidly dimerize to products in which each of the monomeric components possesses an additional electron and an additional proton, relative to the parent monomer1 7). (See Scheme 1)... 

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