Applications of internal nuclear overhauser effects (noe) in organic chemistry : dehydrovoachalotine.

Applications of the intramolecular nuclear Overhauser effect in structural organic chemistry

“…On saturation of H-9, no nOe was observed for H-6. CH3-18 was proved to be cis to H-15 by irradiating the CH3-18 signal, whereupon the signal of H-15 increased by 26 'CH XVI the 5-H signal increased in intensity by 33%. However, saturation of either 3-CH3 or 2-CH3 had no effect on the aromatic protons.…”

Applications of the Nuclear Overhauser Effect in organic chemistry

“…Spectral studies of poncitrin established the partial structure X for this material and the correct assemblage of these groups, XI, was evident when NOE experiments showed that, the O-methyl group was in close proximity to both C-4 and C-6 (11). In an analogous manner t he configuration of the ethylidene side chain in the alkaloid dehydrovoachalotine XII (12) was established by the observation of an NOE between the side chain methyl group and 15 (H). The existance of NOE's between 4-(CH3) and the protons on C-2 and C-6 and between 10-CH3 and 2-H combined with the absence of such an effect between 4-Me and 1(H) and between 10-Me and 5-H, establishes the solution conformation of dihydrotamaulipin-A acetate as that shown in XIII (13).…”