7-Epideoxynupharidine has been isolated from Nuphar luteum subsp. variegatum. 7-Epideoxynupharidine (I) has been encountered previously in connexion with the synthesis of deoxynupharidine (II) and in a study of the stereochemistry of nupharamine. Hitherto, 7-epideoxynupharidine has not been reported as a natural product. The isolation from a natural source and the identification of this alkaloid are now reported. The hydrochloride salt of I gave a satisfactory analysis for C15H24NOCl. The structural similarity to deoxynupharidine was strongly suggested by the virtual identity of the mass spectra. The infrared spectrum (i.r.) corresponded to that reported for synthetic (±)-7-epideoxynupharidine and was different in several respects from the spectra of the other synthesized "deoxynupharidines". Significantly, the i.r. displayed prominent Bohlmann bands in the region 3.4-3.7 μm, which pointed to the presence of a trans-quinolizidine ring system and accounted for the single nitrogen atom. In addition, the i.r. clearly revealed the presence of the furanyl group through display of bands at 6.68 and 11.45 μm. The NMR confirmed this structural feature by showing vinyl resonance bands at 3.69 τ (q, J=1.5 and 1 Hz, 1 β-furanyl H) and 2.78 τ (m, 2 α-furanyl H). NMR data also indicated that both methyl groups of I were equatorial. The spectrum displayed methyl resonance doublets at 9.08 τ (J=3 Hz) and 9.26 τ (J=5.5 Hz), both coupling constants being within the range usually exhibited by equatorial methyl groups in quinolizidines. In contrast, deoxynupharidine (II) displayed the C1 equatorial methyl resonance at 9.08 τ, J=5.6 Hz, but the C7 axial methyl resonance at 9.01 τ, J=7.0 Hz. Nuphenine, possessing a single axial methyl group, gives a methyl doublet at 9.02 τ, J=6.6 Hz. Both methyl resonances of the 7-epi-isomer correspond to the higher field chemical shift and lower coupling constant values exhibited by the C1 equatorial methyl group of deoxynupharidine. The correlation of axial methyl groups with lower field signals and larger splittings and equatorial methyl groups with higher field signals and smaller splittings is a well-known one in quinolizidine chemistry. Solvent-induced shift experiments provided supporting evidence for two equatorial methyl groups. For deoxynupharidine, a change from deuterochloroform to benzene resulted in an up-field shift of 5.0 Hz for the C1 equatorial methyl but a down-field shift of 4.2 Hz for the C7 axial methyl. In contrast, the same solvent change induced an up-field shift of 3.0 Hz for both C1- and C7-methyls of the 7-epi-isomer. Finally, the structure was established conclusively by the observation that catalytic hydrogenation of d6-dehydrodeoxynupharidine (III) produced deoxynupharidine (II) and the 7-epi-isomer (I), the latter being identical in all respects with material secured directly from the plant source. The absolute configuration of 7-epideoxynupharidine is that represented by structure I and follows from correlation through III with deoxynupharidine, whose stereochemistry has been established.