0000000000406998
AUTHOR
Conrad Pascual
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 1H 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 1H and 13C NMR studies. Furthermore, the NOE experiments allowed the assignment of a C-20(S) configuration for teuflavin, th…
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.