AbstractUnambiguous and complete assignments of 1H and 13C NMR chemical shifts for 14 19‐nor‐neoclerodane diterpenoids, nine of them isolated from natural sources and five other synthetic derivatives, are presented. The assignments are based on 2D shift‐correlated (1H,1H‐COSY, 1H,13C‐gHSQC and 1H,13C‐gHMBC) and NOE experiments. The conformations of rings A and B of these compounds are supported by the 3J(H,H) values and they agree with the low‐energy conformations obtained by semi‐empirical calculations. Moreover, the data obtained in this work for 2‐acetoxyteucvidin and a semisynthetic 18‐aldehyde derivative indicate that the configuration at C‐2 of the former and at C‐10 of the latter must be reversed with respect to those reported previously. Copyright © 2004 John Wiley & Sons, Ltd.