[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 stable isotopes of deuterium, carbon-13, and nitrogen-15 has been undertaken, confronting the strong demands for the nucleosides in the NMR spectroscopic study deeply related to structural biology, and the synthetic methods of (2'R)- and (2'S)-2'-deoxy[2'-2H]ribonucleosides, 2'-deoxy[5'-2H]ribonucleosides, [5'-13C]ribonucleosides, 2'-deoxy[5'-13C]ribonucleosides, 2'-deoxy[4-15N]cytidine, [4-15N]cytidine, 2'-deoxy[6-15N]adenosine, and [6-15N]adenosine were developed more efficiently than ever; some oligodeoxyribonucleotides 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 established by the use of a base-labile protecting group, i.e., 2-(levulinyloxymethyl)-5-nitrobenzoyl (LMNBz) protecting group for the 5'-hydroxyl group of nucleoside 3'-phosphoramidites.