Chemical synthesis of C-4 tritium labeled 1′-(2′-deoxy-β-ᴅ-ribofuranosyl) -5-ethyluracil, also named as 5-ethyl-2′-deoxyuridine, a virostatic compound of therapeutic value, is described. The β-configuration has been derived from its optical rotatory dispersion spectrum, NMR spectrum and from its enzymatic hydrolysis.Incorporation of 5-ethyluracil into DNA of phages, bacteria and of mammalian cells has been already demonstrated. To follow the photochemical behavior of 5-ethyluracil in DNA, valid information in vitro can be expected from experiments with the 5-ethyl-2′-deoxyuridine alone; because we have already shown that contrary to 5-ethyl-, 5-propyl- and 5-butyluracil their N-1 and/or N-3 substituted mono and/or di-alkyl derivatives undergo photodimerisation. Similarly, as expected 5-ethyl-2′-deoxyuridine dimerises upon U.V.-Irradiation also (48%). Under the same experimental conditions thymidine dimerises practically to same extent as well (49%). From these results in vitro it follows that replacement of thymidine with 5-ethyluracil into DNA should not essentially alter its normal behavior towards U.V.-light.

Ketosylamin-Umlagerung bei der Umsetzung von D-Xylulose mit aliphatischen AminenDie D-Xylulose wurde durch Spaltung der nach Levene und Tipsons) sorgfaltig durch fraktionierte Destillation gereinigten 2.3-~-Isopropy~iden-~-xy~ulose dargestellt.

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