Reverse phase high-pressure liquid chromatography (HPLC) using columns containing microparticulate materials with bonded octadecyl groups has been developed as a rapid and efficient method for the separation of nucleosides, nucleotides, and, in particular, of protected oligonucleotides which are standard intermediates in the stepwise synthesis of deoxyribopolynucleotides. Reported are extensive studies of the influence of the different purine and pyrimidine bases, of protecting groups, of the phosphate groups, and of the chain lengths of oligonucleotides on their retention on such columns. Further, the application of HPLC in the stepwise synthesis of an oligonucleotide, d(G-G-A-A-G-C-T-T-A-A-C), has been described. The methods, which are herein described, lend themselves to separations on a preparative scale and effect a marked reduction (up to 50%) in the time required for the synthesis of oligonucleotides.
other hand, our own and previous data of others6 reveal that in the presence of a C-8 jS(axial) substituent the C-10 methyl signal appears at distinctly lower field ( = 0.076-0.25 ppm) than in the presence of the corresponding C-8 «(equatorial) substituent. The identity of the C-10 methyl chemical shifts in 1 and 11 thus indicates like chirality at C-8 in the pair of compounds.1964.
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