D-Altritol nucleosides with an adenine and uracil base moiety were obtained by nucleophilic opening of the epoxide ring of 1,5:2,3-dianhydro-4,6-O-benzylidene-D-allitol using the sodium salt of the above mentioned bases. The use of a 2-trimethylsilylethyl protecting group for the O-6-function of the guanine base offers a useful compromise between stability and acceptable alkylation yields of the N-9-position if the guanine base. The cytosine nucleoside was synthesized starting from the uracil congener. The 3'-hydroxyl function was protected with a benzoyl group. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.