The proton and 31P NMR spectra of 2',3'-cyclic uridine monophosphate have been correlated by means of heteronuclear two-dimensional NMR. The spectra depend on the flip angle of one of the rf pulses. This is in contrast to previously reported applications where the 31P nucleus was coupled to a single proton only. For flip angles other than 90 Deg the spectra cannot be readily related to conventional proton spectra and the conformational information is obscured. The resulting multiplets can be analyzed by routine simulation techniques to ext. proton-proton coupling consts. This information, which can be related to the mol. conformation, is often not available from conventional proton spectra. [on SciFinder (R)]