Efficient synthesis of nucleosides labeled with stable isotopes and their application to structural biology

1) A series of synthetic works on nucleosides appropriately labeled with st able isotopes of deuterium, carbon-13, and nitrogen-15 has been undertaken, confronting the strong demands for the nucleosides in the NMR spectroscopi c study deeply related to structural biology, and the synthetic methods of (2'R)- and (2'S)-2'-deoxy[2'-H-2] ribonucleosides, 2'-deoxy[5'-H-2]ribonucl eosides, [5'-C-13] ribonucleosides, 2'-deoxy[5'-C-13] ribonucleosides, 2'-d eoxy[4-N-15] cytidine, [4-N-15]cytidine, 2'-deoxy[6-N-15] adenosine, and [6 -N-15]adenosine were developed more efficiently than ever; some oligodeoxyr ibonucleotides were constructed by the use of these materials and found to be extraordinarily feasible for the NMR spectroscopic studies. 2) A novel approach to oligonucleotide synthesis on CPG has been establishe d by the use of a base-labile protecting group, i.e., 2-(levulinyloxymethy1 )-5-nitrobenzoyl (LMNBz) protecting group for the 5'-hydroxyl group of nucl eoside 3'-phosphoramidites.