Francisco Fernández-Gadea

The C-12 and C-20 configurations of some neo-clerodane diterpenoids isolated from Teucrium species

Abstract A convenient and conclusive method for determining the C-12 stereochemistry of neo-clerodan-20,12-olide derivatives, even when only one epimer is available, is by 1 H NMR NOE measurements. The C-12 configuration of 26 neo-clerodane diterpenoids isolated from Teucrium species has been re-examined by using this type of experiment. The results indicated that all the previous assignments were correct, except for teupyreinin, where the previously assigned C-12( S ) configuration must be amended to C-12( R ). This was confirmed by chemical transformations and additional 1 H and 13 C NMR studies. Furthermore, the NOE experiments allowed the assignment of a C-20( S ) configuration for teuflavin, the structure of which had previously been reported without this feature, and indicated that the previously assigned C-20( S ) configuration for teupyreinidin must be amended to C-20( R ). The validity of using NOE experiments to establish the C-12 and C-20 configurations in these neo-clerodane derivatives has been confirmed by applying it to compounds whose structure had already firmly established by X-ray diffraction analyses.

Diterpenoids from Salvia greggii

Abstract From the aerial part of Salvia greggii a previously known diterpenoid, isopimaric acid, and four new natural substances, 3β- and 14α-hydroxy-isopimaric acids, 14α,18-dihydroxy-7,15-isopimaradiene and 7,8β-dihydro-salviacoccin, have been isolated. The structures of these diterpenoids have been established by chemical and spectroscopic means and, in some cases, by comparison with previously known synthetic compounds.

A rearranged abietane diterpenoid from the root of Salvia aethiopis

Abstract From the root of Salvia aethiopis a new diterpenoid, salvipisone, has been isolated. Its structure, 12-hydroxy-4,5-seco-5,10- friedo -4(18),5(10),6,8,12-abietapentaen-11,14-dione, was established by spectroscopic means and by partial synthesis from aethiopinone. The previously known diterpenoids aethiopinone and royleanone were also found in the same source.

Neo-clerodane diterpenoids from Teucrium lanigerum

Abstract From the aerial part of Teucrium lanigerum , six new neo-clerodane diterpenoids, 7,8-dehydroeriocephalin, teulanigeral, teulanigin, 20-epi-teulanigin, teulanigerin and teulanigeridin, have been isolated. The first of these, 7,8-dehydroeriocephalin, is a natural substance, whereas the other compounds were isolated as their acetyl derivatives after acetylation of an inseparable mixture of natural diterpenoids. The structures of these substances were established mainly by spectroscopic means and, in the case of 7,8-dehydroeriocephalin, by partial synthesis from eriocephalin.

Isoeriocephalin and 20-deacetyleriocephalin, Neoclerodane Diterpenoids from Teucrium lanigerum

Abstract From the aerial part of Teucrium lanigerum two new neo-clerodane diterpenoids, 20-deacetyleriocephalin and isoeriocephalin, have been isolated, together with the previously known diterpene eriocephalin. The structures of 20-deacetyleriocephalin [19-acetoxy 4α,18:15,16-diepoxy-7α-hydroxy-6-keto-neo-cleroda-13(16),14-diene-20 S ,12 S -hemiacetal] and isoeriocephalin [19-acetoxy-4α,18:15,16-diepoxy-6α-hydroxy-7-keto-neo-cleroda-13(16),14-diene (20-acetyl)-20 S ,12 S -hemiacetal] were established by chemical and spectroscopic means and by correlation with known compounds.

A neo-clerodane glucoside and neo-clerodane diterpenoids from Teucrium flavum subsp. Glaucum

Abstract From the aerial part of Teucrium flavum subsp. glaucum a new neo-clerodane diterpenoid, teuflavin, and a new 19-nor-neo-clerodane glucoside, teuflavoside, have been isolated, besides the previously known diterpene teuflin. The structures of teuflavin (19-acetoxy-4α,18:15,16-diepoxy-6β-hydroxy-3-keto-neo-cleroda-13(16),14-diene-20,ξ,12 S -hemiacetal) and teuflavoside (18-acetoxy-15,16-epoxy-19-nor-neo-cleroda-4,13(16),14-trien-20,12 S -olid-6β-yl-2′- O -acetyl-β- d -glucopyranoside) were established by chemical and spectroscopic means and by correlation with known compounds. In addition, the previously known flavone salvigenin has also been obtained from the same source.

Abietane diterpenoids from the root of Salvia lavandulaefolia

Abstract Two new derivatives of royleanone, 7α-ethoxyroyleanone and 7α-ethoxy-12-O-methyl-royleanone, besides the previously known diterpenes royleanone, 6,7-dehydroroyleanone, 7α-acetoxyroyleanone and inuroyleanol, have been isolated from the root of Salvia lavandulaefolia. The triterpenoid O-acetyloleanolic aldehyde has also been obtained from the same source.

Teumarin a neo-clerodane diterpenoid from Teucrium marum

Abstract A new neo-clerodane diterpenoid, teumarin, was isolated from the aerial part of Teucrium marum . Its structure, 19-acetoxy-4α,18:15,16-diepoxy-2β,6β-dihydroxy-neo-cleroda-13(16),14-dien-20,12 S -olide, was established by chemical and spectroscopic means and by comparison with closely related compounds.

6-epiteucrin A, a neo-clerodane diterpenoid from Teucrium chamaedrys

Abstract From the aerial part of Teucrium chamaedrys a new 19-nor-neo-clerodane diterpenoid, 6-epiteucrin A, has been isolated, besides the previously known diterpenoids teuflin, teuflidin, teucrin E and teuchamaedryn B. The structure of 6-epiteucrin A, (12S)-15,16-epoxy-7α-hydroxy-19-nor-neo-cleroda-4,13(16),14-triene-18,6β: 20,12-diolide, was established by spectroscopic means and by correlation with teucrin A.