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

Abstract

<jats:title>Abstract</jats:title><jats:p>Unambiguous and complete assignments of <jats:sup>1</jats:sup>H and <jats:sup>13</jats:sup>C NMR chemical shifts for three structurally complex labadane diterpenoids isolated from <jats:italic>Leonotis ocymifolia</jats:italic> (leonotin, leonotinin and nepetaefolin) and six other related compounds (hispanolone, 7α‐ and 7β‐hispanols, marrubiin, villenol and andalusol), previously isolated from Labiatae species, are presented. The assignments are based on 2D shift‐correlated [<jats:sup>1</jats:sup>H, <jats:sup>1</jats:sup>H‐COSY, <jats:sup>1</jats:sup>H, <jats:sup>13</jats:sup>C‐gHSQC–<jats:sup>1</jats:sup><jats:italic>J</jats:italic>(C,H), <jats:sup>1</jats:sup>H,<jats:sup>13</jats:sup>C‐gHMBC–<jats:sup><jats:italic>n</jats:italic></jats:sup><jats:italic>J</jats:italic>(C,H) (<jats:italic>n</jats:italic> = 2 and 3)] and DPFGSE 1D‐NOE experiments. Copyright © 2003 John Wiley &amp; Sons, Ltd.