ASSIGNMENT OF INDIRECT C-13, H-1 COUPLINGS IN THE C-13 NMR-SPECTRA OF SOME PURINE AND PYRIMIDINE NUCLEOSIDES AND THEIR ANALOGS BY LONG-RANGE SELECTIVE H-1 DECOUPLING

The assignments of the long‐range 13C, 1H coupling constants in the 13C NMR spectra of the base moieties of several purine and pyrimidine nucleosides and their analogues were established by the application of long‐range selective 1H decoupling with low‐power 1H irradiation. The 3J values between the carbons and protons of the pyrimidine ring in these compounds were larger than the 2J values. The conformational preference of these nucleosides in solution was shown to be predominantly anti from the value of the vicinal 13C, 1H coupling constants between H‐1′ and the base carbons through the glycosidic bond. Copyright © 1979 Heyden & Son Ltd.