Complete 1H and 13C NMR assignments of three labdane diterpenoids isolated from Leonotis ocymifolia and six other related compounds

Unambiguous and complete assignments of H-1 and C-13 NMR chemical shifts for three structurally complex labadane diterpenoids isolated from Leonotis ocymifolia (leonotin, leonotinin and nepetaefolin) and six other related compounds (hispanolone, 7alpha- and 7beta-hispanols, marrubiin, villenol and andalusol), previously isolated from Labiatae species, are presented. The assignments are based on 2D shift-correlated [H-1, H-1-COSY, H-1,C-13- gHSQC-(1)J(C,H), H-1,C-13-gHMBC-(n)J(C,H) (n = 2 and 3)] and DPFGSE 1D-NOE experiments. Copyright (C) 2003 John Wiley Sons, Ltd.