Methyl B-D-arabinopyranoside (1) has been stereoselectively aeuterated, by the Treatment of deuteratgd Raney Ni in D 0, to give the 2,3.4-trideutereo-8-D-arabinopyranoside 2 in 33% yield. f t was then converted to 3.4-IsoproFylidene derivative Tb in 90% yield and subsequently derivatired to 2-D-phenylthiocarbonate 4m5%). Compound 4 was deoxygenated at C-2 and was isolated as 2:8 (a:B) an&ric mixture 6 iii 70x yield (based on 4 in two steps). Compound 6 was converted to the free sugar 7, by the treztment of 0.8 M aqueous HCT, which was then successively converted to pentofuranosides: 8+ 9 *g; the crystalline a-chlorosugar 10 was thus obtained in 60% yigld Tn four steps starting from 6. SubsequGtly a-chlorosugar 10 was coupled to different nucleobases of DNA to give 2'.2",3',4'-tetrad=terio-2'-deoxynucleosides in moderate yields. Nuclear magnetic resonance (NMR) spectroscopy has proved to be a very powerful tool for understanding the conformation and dynamics of single and double stranded DNAle3. Despite all currently available techniques to estimate the phosphate backbone conformation, population of the pseudo-rotamers4 or the handedness5 of a DNA molecule by assigning chemical shifts, coupling network of each constituent sugar and estimating interproton distances between each nucleotide residues by HOE measurements, it is still difficult to assess the nobilities of each sugar unit of an oligonucleotide larger than a hexadecamer. An examination of the IH-NMR spectra of an oligomer reveals that it is clearly because of the severe spectral overlap, mainly, of the H-2' and H-2" and H-5' and H-5" resonances from sugar moieties of the oligo-DNA molecule. The problem due to the overlapping of these sugar protons could partly be solved by the selective suppression of absorption(s) at a suitably chosen site in an oligo-DNA by substituting Proton(s) with deuteriumts) while observing the full J coupled net work in the unsubstituted part of the oligo-DNA. Such a selective suppression of information may be useful, particularly, in a long oligo-DNA molecule. Danyluk and coworkers 6-10 have selectively deuterated one or nmre residues in a given segment of nucleic acid which has led to the unequivocal assignment of signals to each base and sugar ring proton, leading to a convenient determination of the spin-spin coupling constants. This group of workers has used labeled mononucleotides. extracted from fully deuterated blue-green algae, synecnococcus lividus. grown in 020. But, the biochemical ways of deuterium incorporation into a nucleoside are limited by the fact that the molecule becomes fully deuterated and when incorporated into an oligonucleotide, the informations due to this particular unit is completely suppressed.
An alternative approach to the solution of the problem of overlapping could be the incorporation of deuterium regioselectively at a particular sugar carbon of a monomer unit. As for example, the