Neoclerodane diterpenoids from Scutellaria pontica

Seven novel neoclerodane diterpenoids, scupontins A-G, have been isolated from the Me2CO extract of the aerial parts of Scutellaria pontica (1-7), together with the known neoclerodanes scutalbin A and scutalpin M. Structures 1-7 were established by exhaustive NMR spectroscopic studies and chemical transformations. Scupontins A-D(1-4, respectively) and scupontins E (5)andF(6) possess unusual [(3¢S,3¢¢S)-3¢-[(3¢¢-acetoxybutyryl)oxy]butyryloxy and [(3¢S,3¢¢S,3¢¢¢S)- 3¢-[[3¢¢-[(3¢¢¢-hydroxybutyryl)oxy]butyryl]oxy]butyryl]oxy substituents, respectively, attached to the C-19 position of the neoclerodane framework. In the case of the 6R,7â-dibenzoate derivative 7 (scupontin G) its absolute configuration was established by the CD exciton chirality method.We thank Dr. A. Rivera and Dr. J. A. Hueso, SmithKline Beecham Pharmaceuticals (Centro de Investigación Básica, Madrid), for the mass spectra. This work was supported by funds from MURST and CNR (Italy), DGICYT (Spain, grants PB93-0154 and PB94-0104), and the bilateral project CNR-CSIC between ICTPN (Italy) and Instituto de Química Orgánica (Spain).Peer reviewe