PHOTOCHEMICAL AND FREE RADICAL INITIATED REACTIONS OF 1,3-DIMETHYLTHYMINE WITH ETHANOL

The photochemically induced reaction of 1,3-dimethylthymine (DMT) with ethanol gives four major alcohol adducts. These have been identified as l,3-dimethyl-6-(1-hydroxy-1-ethyl)thymine ( 1 ), 1,3-dimethyl-5-(2-hydroxy-l-pyl)uracil ( 2 ), and the cis and trans isomers of 5,6-dihydro-l,3-di-methyl-6-(l-hydroxy-l-ethyl) thymine ( 3 and 4 ). The compounds 3 and 4 have been shown to be identical to the adducts produced in y-ray irradiated ethanolic aqueous solutions of DMT. Cyclobutane dimers of DMT are also found in the photochemical reaction mixture. Reaction of 1-hydroxyethyl radicals with DMT, initiated by decomposition of di-t-butyl peroxide, leads to formation of the same alcohol adducts, as well as to DMT adducts containing two molecules of ethanol. The acetone sensitized reaction of DMT with ethanol gives 1,3, and 4, along with a variety of adducts incorporating the acetone sensitizer.