An NMR study of four hispanane diterpenoids is described. In addition to conventional 1D NMR methods, 2D shift-correlated experiments [H-1,H-1-COSY, H-1,H-1-TOCSY, H-1,C-13-HSQC-(1)J(C,H). H-1,C-13-HMBC-(n)J(C,H) (n = 2 and 3)] and 2D H-1,H-1-NOESY were used for the complete and unambiguous H-1 and C-13 chemical shift assignments of these diterpenoids. Copyright (C) 2000 John Wiley & Sons, Ltd.