Improved Synthesis of Anhydrohexitol Building Blocks for Oligonucleotide Synthesis

The synthesis of the four building blocks used for the preparation of hexitol nucleic acids were optimized. The nucleoside analogues with a purine base moiety are best prepared by a nucleophilic substitution reaction, whereas the pyrimidine nucleosides can best be obtained using Mitsunobu‐type conditions.