The short syntheses of the (+/-)-1-cyano-2-(hydroxymethyl)cyclopropyl
derivatives and the related (+/-)-2,3-methanobutyrolactone-2-yl deriva
tives of uracil, thymine and cytosine are described. The key step is t
he condensation of an N-cyanomethyl-pyrimidinedione base with epibromo
hydrin.