ISOTEUFLIDIN, A NEO-CLERODANE DITERPENOID FROM TEUCRIUM-CHAMAEDRYS, AND REVISED STRUCTURES OF TEUCRIN-F AND TEUCRIN-G

A new neo-clerodane diterpenoid, isoteuflidin, was isolated from the aerial part of T. chamaedrys. Its structure, 15,16-epoxy-3.beta.-hydroxy-19-nor-neo-cleroda-4,13(16), 14-triene-18,6.alpha.:20,12S-diolide, was established mainly by spectroscopic means and by comparison with closely related compounds. In addition, the previously proposed structures for teucrins F and G [15,16-epoxy-4.beta.,7.alpha.-dihydroxy-neo-cleroda-2,13(16),14-triene-18,19:20,12S-diolide and 2.xi.,3.xi.: 15,16-diepoxy-4.beta.,7.xi.-dihydroxy-neo-cleroda-13(16),14-diene-18,19:20,12S-diolide, respectively] were revised establishing that their secondary hydroxyl group must be placed at the C-6.beta. position instead of the C-7 position.